I've seen several examples of this: the exact same post showing 2 or 3 times in a row.
This happened to me yesterday when submitting a post, and the software timed out, and reported so on the web page. I hit my browser's "Refresh" button and the post was duplicated. I suspect the same thing has happened with others.
I immediately deleted the duplicate post. Others haven't, maybe not knowing how, or not noticing what happened.