I suggest that when someone finds an exact duplicate of a question he/she should do the following:
In case that original question was solved (an answer was accepted by the author of the question), this new duplicate should have a field (e.g. "duplicate_of") and the server will redirect automatically to that original answered question.
If the original question was not answered, even though this question is duplicate, it is actually a real world unsolved problem that yet another person has come across.
When someone googles for something and the results says "foo bar baz [closed]", he or she then needs to read through the comments and answers in order to find how to get to the other question. That is a waste of time! Why not let the site take them directly to the answer (and probably indicate redirection on the landing page as well).