This request for re-open votes gives an example of a question which has been closed as a duplicate but the "duplicate" question has an answer while the original does not. Curious.
I do not think that such situations should happen, as the answer is more important than simply "who asked the question first". If you are looking for a solution to this problem you will be directed to the unanswered one rather than the answered one. Note that the unanswered question is silent - there is no way of finding an answer by looking at it (no link exists to the answered question - although I might put one there soon...but in general, no link exists).
I would propose either not allowing a question to be closed as a duplicate if the above situation holds (that is, if the "original" is unanswered but the "duplicate" has an answer), or that if a question is an "original" then a list of associated "duplicates" is available and made obvious. (Actually, I think this latter feature should exist anyway.)
Or should someone just flag a moderator to merge the questions?
Or is the best solution to just put in a re-open votes request?...
(I have flagged this as a bug as it might be a bug. I dunno.)