Sometimes Miranda can ask to enter new nick, because "nick on server" even alternative nick is entered in settings. I suspect that Miranda does not check primary nick, but only alternative and it's reason why you still "on server" and Miranda ask for 3rd nick.
Steps to reproduce:
1. You need an independent way for watching on the channel.
2. When you get an described situation, just check logs you will see what was with your nicks.
