When reviewing the question, I left a comment pointing to the possible duplicate and suggested to leave it closed.
Probably such cases are rare, but I was wondering anyway what is the proper way to handle them.
- Should one flag for moderator attention?
- Should one vote to reopen and then, if reopened, vote to close as possible duplicate?
- Should one post a comment and vote to leave it closed anyway?
Of course, I'd prefer a solution that allows the community to decide whether the question is duplicate or worth reopening.