There is a trend of people "surfing" by intentionally posting late blatantly duplicate answers on existing popular questions. This results in rep farming and noise and adds nothing to SO, and often makes things worse. Such answers tend to get flagged as duplicates.

Example: this Python question from 2010: Does Python have a string 'contains' substring method?

  • The question is from back on 2010, Aug 9th
  • The first two answers were posted the same day
    • Both answers refer to in and str.find which are the most classic ways of finding a string in python. The answers are good & short.
  • Now in 2018 & 2019, people are "surfing" on this question wave to post redundant answers. Examples:

There are exceptions/counterexamples:

https://stackoverflow.com/a/49531528/6451573, this one is from 2018 but suggests a totally different, novel way to do it. Contributions like that are always welcome!

When I joined SO network in June 2016, with 1 rep I personally wouldn't have dared to answer such questions. Instead I tried to answer new, less popular questions (duplicates sometimes, like beginners, but at least 25 correct answers weren't showing on the page when I answered...). Maybe it's just me...

What are our options for handling these answers?

  • I'm tempted to use my moderation powers to delete those as clearly trying to benefit from the popularity of the question to garner unjustified upvotes. In fact, I had started to delete them, but undeleted them, because I wanted to have an open discussion with the community.
  • convert the whole Q&A to community wiki: we would see if people want to copy/paste the same answers for zero rep.
    • A toned-down version of the above would be to convert only the late blatant duplicate answers to community wiki
  • Locking IMO would be unjustified; is this what locking is for?


  • 2
    I thought that was relatively common practice, i've seen it done on other popular questions. – Kevin B May 15 at 22:11
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    @KevinB there is even an official guidance on that matter: How aggressively should we maintain and improve very popular questions? – gnat May 16 at 5:00
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    ouch, cross site dupe :) after reading I'm still not sure what to do though. And meta effect made those 3 answers gain votes... the fact that those answers propose alternate methods would vouch for keeping them, but on the other hand the methods suck, but in that case, that would be a downvote. Well... – Jean-François Fabre May 16 at 5:04
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    this thing is naturally complicated because it's the rare case when moderators are expected to do cleanup based on content quality as opposed to their usual involvement in well defined established cases of rules violations (granted this is probably a problem only at Stack Overflow where most of quality-based cleanup is expected to be done by community because of site scale; at smaller sites mods tend to perform such cleanup easier, although also not very frequently) – gnat May 16 at 6:42
  • Makes sense. I'll focus on the areas I know. – Jean-François Fabre May 16 at 6:47
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    well consider asking folks from Python chat room to help you with this: ask them to review answers in the question and share their observations and suggestions in this very meta discussion. Also check flags (including actioned ones) and comments on answers over there, some may provide useful details like which answers duplicated prior one. A less important but possibly also useful thing is to add explanatory comments on answers prior to their deletion... – gnat May 16 at 8:55
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    ...that's a lot of time and effort and normally moderators aren't expected to spend that much, but at 3,5 million views question deserves it (it's in top 30 viewed posts at SO all time) – gnat May 16 at 8:55
  • That's a fact that moderators can't be experts in everything, but I also believe they have to be experts in something. And with all moderators, we pretty much cover a great deal of technologies. I'll wait a while for a real answer. I've seen material for answers in comment already. don't be shy, I'm not going to delete them :) – Jean-François Fabre May 16 at 12:12
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    Burn them with fire. 🔥🐉 – Jeremy Banks May 16 at 13:29
  • Ive been wondering what to do as a regular user when i see such dupe answers on highly-seen/upvoted QAs—I’ve either downvoted or commentes to inform the user that it shouldnt be done. – D. Ben Knoble May 17 at 15:42
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    well, try your luck with flagging. one at a time :) and leave the rest to us – Jean-François Fabre May 17 at 15:47
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    @Jean-FrançoisFabre Some moderators though simply decline these flags with a standard reply... For example, what's the value of the following answer: stackoverflow.com/a/54458718/7851470 ? I flagged it and got "a moderator reviewed your flag, but found no evidence to support it" in my face =/ – Georgy May 20 at 15:10
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    and the same moderator would give different responses depending on if they got up on the wrong foot... it's flagging roulette. But the statistics are on your side. – Jean-François Fabre May 20 at 15:16
  • Is the example really supposed to be locked? The chances of reposting an answer are like 1 in 10 for me, and it can be 0 by simply protecting it. There are some more cool methods discovered which must be added. I also want to add an un-repeated answer. – Black Thunder Sep 22 at 16:34

If you think that a late popular answer adds at least something to existing one, you can edit it and remove all duplicated information. If after such an edit this something looks like a comment or link-only answer or another kind of NAA/VLQ - delete it.

These concrete three answers:

  1. https://stackoverflow.com/a/54552127/9609843

Adds count. Maybe worth downvoting but definitely adds something that is really an answer.

  1. https://stackoverflow.com/a/50887724/9609843
  2. https://stackoverflow.com/a/53923665/9609843

index was already covered in Aaron Hall's answer in much better way, with explanation and performance comparison. These answers show only different wording/formatting but their something has no value.

  • 2
    I'll go with that. My answer is moot because this constructive discussion helped me to make up my mind, not sure I'll be keeping it now. Us mods don't want to be seen as censors who delete content without warning. I've deleted a few more too with that in mind. – Jean-François Fabre May 17 at 5:02
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    @Jean-FrançoisFabre I hope you informed the answerers why their answers were edited/deleted. Preferebly showing a link to this meta discussion. Maybe they have something to say. – sanyash May 17 at 13:52
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    yes, I did. Before & after the deletion. – Jean-François Fabre May 17 at 14:47
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    I disagree with editing out duplicate info. If I write my answer to be complete and self contained, it's because I wanted to cover that material myself for some reason. Such an edit would likely be against the user's intentions. I wouldn't want moderators to be making decisions about what's "unique enough" in my answer to keep and throwing away everything else I wrote. There's a fine line to be balanced with deleting a fully duplicate answer; maybe it would be better to let several users decide that with delete votes in most cases. – jpmc26 May 18 at 21:39
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    @jpmc26 every case can be handled individually and carefully. For example Aaron Hall's answer starts with duplicate info too, but it shows much more additional information and as you said, this duplicate info just makes it complete. Nobody will edit and remove this duplicate info. – sanyash May 18 at 21:54

I don't think converting them to CW is fair. If they posted it solely to earn rep... they're not alone, a lot of answers are posted for that very reason; on old questions, new ones, and all in between.

If it's an answer that doesn't add anything that hasn't already been covered in another answer, delete it. Otherwise it is a valid answer regardless of how old the question is.

Essentially... if it's worth keeping, I don't think we should penalize the user by making it a CW to prevent rep gain. Voting on it's quality/usefulness is still fair game.

  • 4
    at least one real answer. I don't agree though :) Some users post CW answers on their own because they feel it would be unfair to gain rep from content that isn't theirs (but copies from comments, mixes from other answers). That seemed to be the case here. I'll edit my answer (and your answer seems to reply to my answer, not to my question, I'll fix that too) – Jean-François Fabre May 16 at 19:29
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    @Jean-FrançoisFabre But they're not supposed to be doing that either. The purpose of CW is to indicate that a post is a collaborative work of multiple people, not to indicate that the author doesn't want any rep. The latter is simply the consequence of the former. – Servy May 16 at 19:50
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    I agree with the collaborative part. Maybe converting to CW is a half measure (even if we can see those posts as an unwillingly collaborative effort from historical answers :)), but I'm using the tools at my disposal, better that doing nothing at all. Note that the "delete" button is still active. There's a gray area in CW as well as in those answers. I also didn't want to stealth-delete those answers without discussing with the community first but if enough people/votes convince me that I should, I will – Jean-François Fabre May 16 at 19:52
  • To me it was not obvious: CW means Community Wiki. – slartidan May 18 at 18:28

This problem seems to be exactly what the Protected question status is for. It prevents low reputation users posting answers because the the question is attracting low quality answers (which tend to come from low reputation users). So if you see this happening to a question, and you have the privilege to protect questions, use it.

Arguably, all canonical questions should be protected: by the time a FAQ has become a canonical question, it has had plenty of opportunities to get easy answers, and has been answered by several experts, so it is very unlikely a low reputation user can add something useful to it.

  • yes, but the "protect" feature doesn't prevent someone with 50 rep from posting a repeated answer. That's why I've used CW lock. – Jean-François Fabre Jul 10 at 19:41

This self-answer isn't what I'm going with after reading other answers. I'm leaving it here so if someone else suggests the same they can see community disagrees

As I didn't get a full answer yet, I rolled my own, based on very good comments on the question.

I chose to convert them to community wiki. The help text of the convert to wiki option reads:

Community wiki questions don't accrue rep and have a lower full editing reputation threshold. Questions should be manually converted to community wiki when they are marginal fits or 'list of X' questions that contain enough value to avoid deletion. This affects the question and all answers.

The help is not 100% suitable for answers, but:

  • there's borderline "enough value to avoid deletion" in the 3 quoted questions
  • readers can downvote them without losing rep, and edit them more easily
  • that could deter future posters to post the same thing again
  • they remain undeleted so no precious information is lost

I failed to find a 100% exact answer, even if the alternate solutions that weren't present in historical answers aren't practical and not used, this is only my opinion. So community wiki it is (but everything can be deleted/reverted if any good reason occurs)

Some users post CW answers on their own because they feel it would be unfair to gain rep from content that isn't theirs (but copies from comments, mixes from other answers). Sounds that it's the case with those answers.

On the other hand I deleted https://stackoverflow.com/a/48241340/6451573 because it didn't answer the question like at all, also surfing on the question popularity to propose a solution to another problem. With 3 million views we cannot afford nonsensical answers.

I will try to treat answers to other popular questions in the technologies I know the same way:

  • delete if same exact solution, doesn't add value
  • leave if different enough with added value in the differences
  • convert to community wiki if can't decide
  • 7
    FWIW 20 hours is not a big amount of time for something as sweeping as this topic. I would have encouraged waiting a couple days, or at least until someone else answered, before drawing a conclusion. – TylerH May 16 at 18:54
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    as said in my post, nothing is irreversible and the response was moderate (only 1 deletion). I chose this way to get it done ATM but if a consensus builds in favor of a deletion, we'll see (and other python mods can help too). Also note that I had a ton of answers as comments. – Jean-François Fabre May 16 at 18:56
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    Community wiki isn't really meant to be used as a rep-denial tool. I understand how you could consider it a half-measure between deletion and preservation, but I think it would be a better practice to choose one or the other instead. – Jeremy Banks May 16 at 22:02

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