I'm somehow appearing in the player list with my alt acc. for testing. I think i closed the game in windowed mode via the "x" for closing window. Maybe that could help. But strange things are: i do so with my main acc as well, he's not in the list then. And i logged in again in my alt acc. and logged off correctly, but he still appears in the list. So maybe it's not useer side, but server side?
Ah something came to my mind: i think i tryed to log in, when my main acc wasn't logged off already, getting the error: no response from server and closed the window. Maybe the server registrated my alt acc as logged in anyways or it's sth ip-based?
Good luck in finding the problem