When you have close votes remaining, you can always see duplicates used as close votes by pretending you're going to close vote (select the 'exact duplicate' reason) and proceed. But, after the recent changes to that part of the UI, you can no longer click-through if you are out of votes:
Scaled to 75% because that box is ridiculously big.
Feature request: If a user has enough rep to close-vote, then always allow that user to see duplicates used in other close votes, even if that user has cast their limit of close-votes for the day.
This could be done with a link beside the blue
, or something else. I really have little preference on how to make them visible, I just know it would be useful.