Today, the behavior of duplicate close votes was changed so that a question can only be a duplicate close vote target if it has an upvoted or accepted answer. I think that this change is not a good one and that it should be reversed, for the following reasons:
The purpose of being able to close questions as duplicates is to aggregate all answers to a question in one place. This new change makes that more difficult because if a duplicate question is asked and the original does not have an answer, neither will be closed. And as @BenBrocka points out:
what happens when one of the questions gets an answer? The effort to find the duplicate earlier goes wasted and someone else has to find the dupes yet again after one is answered, and know which one is answered just to be able to close.
Whether a question is a duplicate of another is entirely independent of whether it has an answer.
This change is open to abuse. As @fbueckert points out, one could
Ask question, get no answer, ask same question with sockpuppet, continue until answered.
Abusive behavior obviously isn't allowed, but if someone is even a little clever it could take two or three iterations to realize that this is what's happening and that it's not just different people asking the same question around the same time (That happens sometimes on Arqade when new popular games are released).
This change provides minimal benefit. It's true that new users have trouble getting old questions attention, and asking another question is often their only recourse. But if a question is old an unanswered and the new question really is identical, it would probably take a bounty to get the question answered anyway. And if the new question is not identical to the old one, this shouldn't be a problem anyway.