I don't find it wrong in anyway as once even I did it to post comments in a Signature campaign I was a part of but my second post was deleted even though it was not off topic and it wasn't merged. I don't get paid to post in my signature campaign but well it is considered as bumping a thread twice and so one needs to clutter up their post to avoid double posting or wait for another person to reply and then post another comment.
So there isn't a clear rule and each mod. "moderate" thanks to hi judgement (not a problem) but I will see if that mod will merge those posts from those users or not. This is why I have opened that thread (but first I sent a pm to that mod).