I'm not talking about exact copying, failure to give credit, or one person passing off another person's answer as their own.
Rather, I'd like to know what the best practice is when one user answers a question with an answer that is either:
effectively identical to an existing answer, and not really stylistically different (so there is nothing about it that would make it preferable to the existing answer)
effectively identical to an existing answer, just with some information removed (but the information that was removed was useful, and was not false, misleading, or even confusing)
I think this doesn't happen only (or even primarily) from one user copying another user's answer. Rather, when a question has a simple enough answer, answers that look extremely similar may be posted ...if subsequent answerers don't look to see what other answers have been posted, first.
(Another possibility is a user starting to compose a 2-line answer, but taking an hour or more to finish it, and then another answer that is similar being posted. I consider this to be possible, but unlikely.)
As one example of this, consider this question, where this answer was posted, and then about an hour later this answer was posted.I've edited one of those answers for unrelated reasons, to improve it, so this is no longer a good example. If anyone can replace it with another/others, great! If anybody thinks this whole text should just be edited out entirely from this meta question, I'm OK with that too.
Should these be...
just left alone?
flagged for moderator attention?
or something else?
I'm reluctant to downvote something like this because the answer is not any of the following: wrong, misleading or otherwise dangerous to users, very low quality, or not really an answer to the question that was asked. I usually try to downvote answers that meet any of those descriptions (and cannot readily be improved), and to not downvote answers otherwise.
Sometimes these second, equivalent answers get upvoted, and are then shown higher than the original answers, so they're upvoted some more. This seems counterproductive to the goal of getting us to answer questions that still need answers (whether or not they already have answers), and then moving on to other questions that need answers.
Please note that I do not believe this is the same as the situation discussed here. In this situation I'm asking about, subsequent answers are posted with the same or less information. In that situation, subsequent answers are posted with more information or partially overlapping information.