I ran a dual output Radeon video card with two different flat panels but i have to go into here etc/x11/xorg.conf there you will find the xorg config file. You need to edit the xorg.conf file there with a text editor like kate. In order to do this you open up a terminal and type " kdesu kate ".
dSectionSection "Monitor"
Identifier "monitor1"
VendorName "Generic"
ModelName "Flat Panel 1280x800"
HorizSync 28.8-90
VertRefresh 60
# Monitor preferred modeline (60.0 Hz vsync, 48.9 kHz hsync, ratio 16/10, 108 dpi)
ModeLine "1280x800" 68.9 1280 1301 1333 1408 800 804 808 816 -hsync -vsync
# TV fullscreen mode or DVD fullscreen output.
# 768x576 @ 79 Hz, 50 kHz hsync
ModeLine "768x576" 50.00 768 832 846 1000 576 590 595 630
# 768x576 @ 100 Hz, 61.6 kHz hsync
ModeLine "768x576" 63.07 768 800 960 1024 576 578 590 616
# modeline generated by gtf(1) [handled by XFdrake]
ModeLine "1280x800_120" 181.21 1280 1376 1520 1760 800 801 804 858 -HSync +Vsync
# modeline generated by gtf(1) [handled by XFdrake]
ModeLine "1280x800_100" 147.89 1280 1376 1512 1744 800 801 804 848 -HSync +Vsync
# modeline generated by gtf(1) [handled by XFdrake]
ModeLine "1280x800_85" 123.38 1280 1368 1504 1728 800 801 804 840 -HSync +Vsync
# modeline generated by gtf(1) [handled by XFdrake]
ModeLine "1280x800_75" 107.21 1280 1360 1496 1712 800 801 804 835 -HSync +Vsync
I showed you this section on my xorg.conf file on my toshiba laptop which is only single resolution. However you can change this by changing each resolution in the mode line of each par and under monitor under model name.
# modeline generated by gtf(1)