Mythbuntu starting 2 instances of mythfrontend on login?
.. and other such startup weirdness? Such as mouse and remote not working after login too.
The problem’s in xfce caching the desktop session to resuming, and then also auto-starting etc.
The sessions are stored in ~/.cache/sessions just delete them all, or remove that directory (and make a new one in its place). And be careful about saving sessions when you logout.