Comment 6 for bug 1335498

I second this bug.

I meet multiple launches all the time.

I suspect that in my case it's caused by the fact that my applications (hexchat and pidgin) are added to the 'autostart' menu:

Settings->Session and Startup->Application Autostart

And I suspect that their existence is also saved into some 'session state' upon logout, so xfce starts them twice, as a piece of the session and as a piece of the autostart.

Meanwhile you can't just remove them from the autostart, because you don't always need to save the session.