When closing a question as duplicate, currently you can view what other people suggested as a duplicate. But when you cast your own vote, you still have to manually enter in the question ID or search for the question again. Often text-searching is hard to find the same question, and it's ugly to copy-paste the question ID back from another tab.
I think you should be able to "agree" with a suggestion already on the table or add your own.
Proposition 1 - Click on a suggested question's link to choose it as your possible duplicate. Maybe a "Choose This" or "I agree" link?
Proposition 2 - Click on a suggested question's link to open the question in a new tab as it does currently. On the opened page is a new button to "Select this question as possible duplicate" to close the tab and select the question.
Which one feels better (or none)?