If you are suddenly IP Banned for no reason and you can login to another account, your not actually IP Banned.
Think about it. with your head. IP Ban means everything from your IP is banned, and when you can log onto one acc but not the other, you obviously NOT ip banned are you. No.
It just means you tried to mass login and when server restarts u can relogin.
However if you get "please use a different world" your acc is bugged and needs to be reset