With the restyling of the Close/Reopen review queues, this appears to have been fixed, as that particular dropdown doesn't (seem to) exist anymore.
When reviewing this close vote, I saw that the duplicate question on the "Duplicate" tab in the review queue showed "4 answers" (1 answer, 3 deleted answers):
Because I have 10K+ and can therefore view deleted posts. But in the Close as Duplicate dialog, it shows "1 answer":
Which makes it just slightly confusing. Can there be a 10K check to fix that, if there isn't one already?