Close-as-duplicate is the right answer, though there's a special place in hell for people who close-as-dupe without referring to which ticket is the dupe. In my previous role as a software tester, there'd be all sorts of tickets closed-as-dupe, yet I couldn't find them. Turns out that they had no common search terms and were (usually) not actually dupes, just that the coders didn't want to think too hard on the issue. I'm fine with "won't fix" or pushing to backlog, but let me see what the dupe is.