Are the tags: reopen-request, close-reasons, closing, reopening duplicates? Ought some be removed?
No as they are not duplicates:
reopen-request is for a post that specifically asks for the Community to consider voting to reopen a post.
close-reasons is when OP is asking the Community to discuss on the possible reasons a question was closed. This is independent from a request to reopen, and should be more focused on the reasons why it was closed, as to improve on future posts.
closing is about the process of closing itself, as well is reopening for the process of reopening a post.
Perhaps you have seen them mixed up sometimes, and thus your confusion. But all users should be aware of these differences to tag accordingly.