Re: can't get dualhead separate screens to work
I am not sure how to disable one but for a dual screen setup I don't use metamodes at all.
In this set-up I have screen :0.0 and :0.1 so you cannot move window but I use it as you mention - work on one, view movie on second.
In any case, read your /var/log/Xorg.0.log to see what Xorg recognize even if it does not work (eg. DFP0 or DFP1, CRT0 or CRT1, etc...)