option "Metamodes" "1280x1024,1024x786;1024x786,1024x786;800x600,800x 600"
First 1280,x1024 on LCD and 1024x786 on TV
second 1024x786 on both
third 800x600 on both
option "TwinviewOrientation" "Clone" means both displays shows the same.
Hope that will help.