i believe it goes (SCREENRES X, SCREENRES, Y, PIXEL SPACES X, PIXEL SPACES Y,
So to run 1024x768 on your first screen it should be
1024,768,0,0 - donates 1024x768 at the 0 pixels over, 0 pixels down (top left).
for the second screen you will require:
1024,768,1024,0 - donates 1024x768 res,1024 pixels over, 0 pixels down.

Thats assuming your using vertical span im not sure on how to work it duel view