Twice now I've seen a post duplicated in the main feed but where the second one opens a completely different post.
I captured a screen recording of it but it's too big to upload directly. Here's a screenshot--the second post opens something different...
Look at the top of each post where it says "in [community@server]"
These are in separate communities so they aren't duplicate posts in the way you're thinking
Per OP, the second post is directing to something different. It’s duplicated visually but not an actual duplicate.