Sorry, I know it's late but this is something that at least one other poster and I have noticed. And, in my case, not just now.
I've tried copying and posting a poster's name. If I then put @ immediately before it and a 'return'/bent arrow immediately post it, it skips to the previous name I've copied and pasted.
If I put a space before the 'return', the name I've just c&ped remains.
I can show you a "for instance" on a thread here if I'm not making myself clear.
PS Also, every time I preview this I get "Access denied". I ignore that and press "Ok" and it works.
I get the same thing sometimes with "Post". I just press "Ok" but it might be one of the reasons you occasionally get double posts.
And, yes: have pressed "Ok" on my preview of this, despite being told "Access denied".
Will still press "Ok" on post...