I've noticed that using the preview feature when you're about to place a post results in a "replied to" action in recent activity of your homepage. So say for example, if I preview my posts twice before posting, my recent activity will show that I replied to a particular post 3 times rather than once.

I believe it doesn't affect one's post count, and it's only a small issue. But still maybe something to look into?
You have just helped us recreate a bug, we didn't know why some people were showing to post duplicates! That's fantastic, thank you very much for letting us know [Y]
No worries at all. Happy to have helped.