I answered this question the other day. It was one of those cases when I just happened to see it right as it was posted and it was a fun question that I knew something about. So I gave an answer (which received more votes than it probably merited). I'm not in the habit of searching for duplicates before answering (especially when searching for a duplicate is more difficult than answering). It turns out that this was a duplicate and was closed as such.
My question is: what will happen to a question that was closed because it was a duplicate? I suspect that it will be (at some future date) deleted. If this is the case, do answers to the duplicate get deleted as well? or are they migrated as a (late) answer to the original question? Does any of this change if the new (closed) question has more upvotes/views than the original question (open)?
My personal test for "duplicate" is: Would an answer to question A answer question B just as well? If so, then question A and B are duplicates. In this case, answers could be moved (without loss of context) and preserved. Of course there are two issues that you'd run into: duplicate answers and having to resolve which answer is the "accepted" answer.