In this 2009 blog article, Jeff Atwood wrote :

As we get more and more questions in Stack Overflow, the issue of duplicate questions becomes more pressing. The odds of any question being a duplicate, however small, increases with the total number of questions in the system. So it's worth considering: what makes a question an exact duplicate? As I see it, there are three classes of duplicate questions, from most clear to least clear.

  1. Cut-and-paste duplicate questions. These questions are the very definition of exact duplicates; they are typically from users who willfully take the very same question and post it again. Either they're not satisfied with the speed of answer, or they just don't know what they're doing. We rely on Stack Overflow users to vote down these "questions" and flag them for moderator attention. These sorts of duplicates are typically deleted as soon as we see them, as they're borderline abuse of the system. They often don't get answers, so this is fairly easy to deal with. No grey area here.



Note the final words of this quote :


This means that Jeff Atwood believes there is merit in having multiple questions on this site that are very similar but not identical duplicates.

Now, suppose you have two questions A and B that most reasonable people would consider to be "borderline duplicates". Suppose someone writes an answer for question A that is also suitable for question B.

Would it be OK to post the same answer to both question A and B, when these questions are "borderline duplicates"?

And IF you believe it is NOT OK to post the same answer to both question A and B, when these questions are "borderline duplicates", what alternatives do you suggest?

Should one...

  • Flag question B as a duplicate anyway (even though it isn't) and not answer the question, even though that answer may actually be the best answer for that question?
  • Rewrite the answer to question A so it looks different but still contains essentially the same content?
  • Answer to question B with a link to the answer of question A?
  • ...

How to deal with duplicate questions is obvious to me, but thus far no one has been able to tell me how to deal with "borderline duplicates" or other cases where questions aren't exactly duplicates but a single answer is helpful, practical and to-the-point for both questions. Please tell me what's considered appropriate in those situations, so I know what to do whenever I encounter such questions.

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    At no point in my 5+ years on SO have I ever considered copying and pasting identical text and code in an answer across multiple questions except with the intent of quoting a previous answer in a new one for context. It's ok to tailor answers to borderline dupes - I do it all the time - and it's ok to cross-reference previous answers for context. But if a potential answer consists of nothing but a quotation of a previous answer, that's how I know I should be voting to close as a duplicate instead, borderline or not. – BoltClock Jan 23 '16 at 4:15
  • So.... if a borderline dupe is tagged as a dupe and the answer is on the dupe-target... It helps whoever comes to the question. It also incidentally gives the OP the same rep (if we exclude accepts)... so honestly I don't see why you fight so hard when the community tells you to close them as dupes. – Patrice Jan 24 '16 at 14:47
  • @Patrice As I see it, borderline duplicates and actual duplicates are two véry different things, and thus require different treatment. Judging by Jeff Atwood's article, Atwood seems to agree with that. I just find him (or anyone else for that matter) unclear on what exactly the proper treatment for borderline duplicates is. – John Slegers Jan 24 '16 at 15:12

If a copy-paste answer works for a new question, then it is a duplicate irrespective how different the questions are. I believe that the final quote is about exactly such a case of a "duplicate as signpost question" rather than talking about borderline duplicates.

If you know that a particular question is a borderline duplicate, but you believe that it is sufficiently different to require new answer, then make sure to clarify it on the question (at least leave a good comment, such as: "partially covered by {link to other question}, but different because of {reason}"; or maybe even edit the post). Then, if you can, provide an answer that solves the new problem and links/summarizes to an existing answer for the rest.

For some borderline cases, closing as duplicate and adding a comment on both questions to cover the new case may be the better option (like "same applies for 'operator +' as shown here for 'operator *'").

  • At this point of time I would just delete the copy pasta question... no need to keep it around. – Braiam Jan 25 '16 at 3:28

To compile what I commented in the meta post that inspired you asking this question:

Questions that can be answered with the same answer are duplicates. See, for example, over 2000 duplicates of What is a NullPointerException, and how do I fix it?. Each of those is "unique", but the problem and answer is the same in essence.

Given how complex any programming question is, for there to be two truly separate questions that actually have the same exact answer is beyond improbable. They are duplicates. The goal of Stack Overflow is not to answer every minor permutation of a question, especially with carbon copy answers.

If you don't feel strongly enough that something is a duplicate, then fall back to rule two: do not copy answers. If you are willing to argue that two questions can be unique if they are worded differently enough, then you must also be willing to apply that same rule to your answers.

In summary:

  1. If two questions share the same answer, they are duplicates.
  2. Do not copy answers.
  3. If you can't accept 1 and 2, move on to another question.
  • The same answer is possible. The same good answer, that's unlikely. – Deduplicator Jan 23 '16 at 8:32
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    It has been a point of contention that multitudes of reasonable debugging questions are needlessly being closed as a duplicate of the NPE canonical simply because the contain the word NullPointerException, or contain code which would trigger a NullPointerException. I think that may not be the best example. – user4639281 Dec 7 '16 at 18:43

There should be a simple way for a moderator/or anyone to turn a duplicate answer into a link to the other question. That way the person still finds the answer, and the site can some how better manage duplicates.

There could be an easier way for a person to say "Hey! my answer could possibly answers these three questions"

Just simply deleting them does not help the user, which is the main goal of this site.

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    Actually, there is a way to do this, and it's something you can do! Click "flag" on the question, select "duplicate of", and enter the url of the question. Then you don't have to post duplicate answers and future users are pointed to the question that does have your answer. (And if the question is closed as a duplicate and has no answers, unauthenticated users are automatically redirected to the question you linked it to.) Everyone wins! – Kendra Dec 7 '16 at 17:36
  • so WHY don't the moderators do this???? – Eric Schneider Dec 7 '16 at 17:40
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    Because the moderator may not have enough expertise to tell the questions are for sure duplicates. We only have about 20 moderators, last I checked, and they don't have expertise on every subject. They do know that your answers are exactly the same, but they can't always confirm the questions are duplicates. You should be doing that yourself before posting your duplicate answers. – Kendra Dec 7 '16 at 17:41
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    He obviously found duped answers?, like I said moderators are more worried about policy than helping people – Eric Schneider Dec 7 '16 at 17:43
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    The duplicate answers are pointed out by the system, and they have to be exact duplicates, as far as I'm aware, before the system will flag them. If you're only posting similar answers, a user would have to bring that to the moderator's attention... And chances are that user would flag/vote the questions as duplicates. Mods can tell when two pieces of text are character for character the same, but they cannot always tell that two questions are asking for the exact same thing. – Kendra Dec 7 '16 at 17:45
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    Moderators are janitors to clean up messes on the site. We, the users, are the ones helping control things like closing questions and such. You have the power to flag questions yourself, and the expertise (I assume) to tell if those questions you answered were asking for the same thing. Moderators don't have that for every single tag on the network, so they're trusting you and users like you to point duplicate questions to the right places and get them closed. – Kendra Dec 7 '16 at 17:47
  • so the system, should be able to transform them to a link & possible duplicate question. – Eric Schneider Dec 7 '16 at 17:47
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    No. Just because you posted duplicate answers does not automatically mean that the questions are duplicate. As stated in the first comment on your meta question, if the questions aren't duplicates, you should tailor your answers to address the answers specifically. Then the moderators won't step in and delete your answers, as they are no longer duplicate answers. – Kendra Dec 7 '16 at 17:48
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    Another problem: This question does not have an upvoted or accepted answer – Eric Schneider Dec 7 '16 at 17:52
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    In regards to "WHY don't the moderators do this????" - you and everyone else on the site are the moderators. It is in your power, and something you should be doing. – Oded Dec 7 '16 at 18:26
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    Yea, see above I couldn't do it. ad it's still bad policy to delete, people possibly lost out – Eric Schneider Dec 7 '16 at 18:35
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    Whatever; I'm done trying to help others. For now on, I'm not wasting my time on the site, I'll just use google like everyone else... – Eric Schneider Dec 7 '16 at 18:40

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