I haven't had any luck finding out by searching this forum, but how do I switch between xserver sessions setup via the seperate xserver configuration?

I want to have my laptop display and my new Dell S2009W to display different stuff, since stretching one session across both goes nuts when I take the laptop with me and mirroring isn't exactly what I want, I want to use one session per screen, however, I can't control the extra session!

How can I workaround this or is there some secret shortcut for it I haven't learned yet or am missing?