I keep seeing a strange pattern. A user on StackOverflow will post a question that has been asked before, but will ask it in a slightly different way such that a close-with-exact-duplicate is not appropriate.

So I'll answer the question, focusing on the differences, and referencing the related articles. No big deal.

But then within a relatively short period, a completely different person will ask almost the exact same question! Again, subtle differences, not exact dup. I get a bit of déjà vu - "wait, didn't I just answer that?"...

Checking out the two posters, they always appear to be different people. Not only do they have different usernames, but they write with different grammatical styles, misspellings, etc.

The only thing they appear to have in common is usually a very low rep (1 to 50), and few details in their profiles. Sometimes they are completely new, but often they have been a member for two or three years. (Who does that? 31 rep after 3 years? Really??)

Latest example:

So while they are slightly different, both involve differencing C# DateTime objects and evaluating TimeSpans in LINQ. Nothing wrong with either post that would deserve a moderator flag, but I could swear that these posters could be twins. Perhaps this is a bad example, since they are posted 4 days apart. But many, many times I see this just a few hours apart.

Is it just me? Do I have double vision? Perhaps I'm going crazy. (And yes, that's a valid answer, if you want to take this question from a psychological point of view.)

Anyone else have this experience? It happens to me at least once every other week.


  • These are co-workers (or students in the same class) trying to solve the same problem and both jumping on StackOverflow at similar times.
  • Selection bias, since I follow particular tags closely.
  • It's completely coincidental.
  • I'm seeing patterns in the chaos that aren't really there.
  • I'm seeing patterns in the chaos because they DO exist!
  • I'm loosing my mind and these are the early warning signs.

Can anyone shed some insight as to which of these theories might be more plausible than others and why?

Is this anything to worry about from the perspective of improving the quality of questions on the site?

closed as primarily opinion-based by Martijn Pieters, Aza, hims056, wax eagle, John Saunders Jul 30 '13 at 19:26

Many good questions generate some degree of opinion based on expert experience, but answers to this question will tend to be almost entirely based on opinions, rather than facts, references, or specific expertise. If this question can be reworded to fit the rules in the help center, please edit the question.

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    Students in the same class; you just helped two people do their homework. :-) I do see this happen often enough; if at all possible, I try to mark one as a dupe of the first I've encountered. – Martijn Pieters Jul 30 '13 at 15:44
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    However, you don't seem to ask for feedback other than 'anyone else have this experience?' which can only be answered with 'sure, me too' or 'nope, never seen that'. – Martijn Pieters Jul 30 '13 at 15:46
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    This, for sure : I'm loosing my mind and these are the early warning signs. :) – Jonathan Drapeau Jul 30 '13 at 15:50
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    I'm sure I've seen a post like this before somewhere.... :) – George Duckett Jul 30 '13 at 15:51
  • @MartijnPieters - Updated with more directed question at the bottom. Thanks. – Matt Johnson-Pint Jul 30 '13 at 15:52
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    who has 31 rep after three years? A person who asks about 1 question a year and gets about 2 upvotes for each question. Or one every 3 months, half get no upvotes and half get one. A perfectly normal person, in other words. (Unlike say me, who is abnormal in this regard.) – Kate Gregory Jul 30 '13 at 15:58
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    Why do I get déjà vu reading this question? Does it feel lately like all questions have already been asked and answered and there is nothing more to do? "I see a new question and start answering it only to realize after the first written sentence that I have answered similar questions five times over or seen them answered some ten times or more..." – gnat Jul 30 '13 at 18:15

Beginners ask questions about the same sorts of things all the time. These are just patterns that recur in the world. People put timestamps in a database, then they want to do math with them, they think LINQ is cool but it's not clear how to do what they want. Similarly people want to print things with page breaks, they get particular error messages, they make particular errors of thought that others have made before.

You need a much broader definition of duplicate. Focus on the part that says "your question has an answer here". If the one you saw before will help this person, vote to close as a dupe rather than answering. This will give them the banner right away and it's flat out quicker than you typing a tailored answer. I think it's telling that you write Nothing wrong with either post that would deserve a moderator flag, - this suggests to me that you seeing marking as a dupe to be something that is wrong with a post. When you mark something a dupe you are giving a gift to the asker - your answers are already here, have a link. (more on this at another answer of mine.)

If the original only has answers that are super specific, consider adding a very good general answer and sending everyone who asks a variant of the question to the excellent original.

  • It's a gift to the asker unless people start piling on the down-votes because the user didn't search first and find the duplicate on their own. – Aaron Bertrand Jul 30 '13 at 16:26
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    I used to tell my children on the topic of reporting wrong doing by a friend: if she gets in trouble, it's because of what she did, not because of what you said. It's not your job to keep her out of trouble. Similarly, if a low-effort question gets downvoted, it's because it is low effort, not because someone marked it as a dupe. It's not your job to hold off on an accurate action out of some sort of pity for the author of the question. Vote questions, not people. Help people, including by showing them where the answers are waiting. – Kate Gregory Jul 30 '13 at 16:28
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    Whoa, hold on. I'm not saying don't mark it as a dupe because it might increase the odds of down-votes. I'm just saying the OP might not consider it that much of a gift. Especially since, on top of that, they almost invariably insist that their issue is just a little bit different than the other question you've identified (and often they will say so without even reading the answers). – Aaron Bertrand Jul 30 '13 at 16:30

To paraphrase Leo Tolstoy's famous words,

Correct programs are all alike; every incorrect program is broken in its own way.

Beginner programmers are often unaware of the same language mechanism, the same programming technique, or the same way of using a library. Not knowing the name of what they are looking for, they ask a question in their own words. They tend to make identical mistakes, too, contributing to the ever-growing pool of questions of non-working if statements when they compare Java strings, non-working Replace methods when they ignore return values of methods invoked on immutable objects, and non-working while loops when they call feof before reading a value. They may even spend some time searching Stack Overflow for their problem, and find nothing: the trouble is, they search by describing the symptoms that they see, not by the name of their general problem. But since every unhappy family is unhappy in its own way the symptoms are different, they do not find the answer that could spare them typing up a question, making "déjà vu"s a reality.

  • Corollary: Every program is incorrect, in some way. I have yet to see a non-trivial program that didn't contain at least one bug. – Robert Harvey Jul 30 '13 at 16:58

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