title: Cassandra: Insert multiple rows containing different data with the same set of primary key values
body: <p>Say I have 2 rows of time-series data that have exactly the same timestamp etc for the primary keys. The only difference is the rest of the data are different.
  So if set 1 has [timestamp, other keys...], value_col1, value_col2, then the value_col1 and value_col2 for set 2 will have different values than set 1.</p>
  
  <p>Now if I put those sets into one batch to be inserted or very quickly using seperate inserts queries, the result I see in the database can be somewhat inconsistent: it can be that value_col1 from set 1 is combined with that of value_col2 in the final row.</p>
  
  <p>It took me the whole evening to find out this is actually a bug (or maybe intended behaviour...) I have my workaround now using a slightly increased timestamp for set 2. The sympton won't be noticed in many cases, but in my case where col1 is the partial decoding key for col2, then I have a problem!
  Does anyone have the same problem or knows where the problem actually lies?</p>
  
  <p>I'm using cassandra-node drive on nodejs 5.0.0 with cassandra 2.0.14.</p>