Comment 9 for bug 366270

Having the exact same issue using 12.04 LTS.

Curiously enough it worked as expected for a little while (putting off the lvds and proper resolution on vga) but, perhaps due to an update, it now by default clone the lvds and force both screens to be 1024x768 (wich is probably the only compatible resolution between laptop & 22" lcd connected on vga.