@Phases,
I've noticed that the most common theme preventing moderator actions on threads revolves around the last post in the thread. In cases where there is only one post (the majority of the duplicates) the OP is both the first and the last post.
In this thread I was able to merge the many duplicate threads into a single thread.
http://androidforums.com/threads/sprint-note-ii-cannot-flash-new-rom-now-stuck-in-cwm.929934/
I was able to delete all of the other posts, including the OP (since restored) except the last post in the thread. When the member posted another dupe I was able to merge that in and then delete what was previously the last post with no problem but was unable to delete the new last post to the thread.
I hope that makes sense.