Comment 1 for bug 46969

I filled a similar bug report and I can tell you its not related to multihead support.

99% of the computers you buy retail come with integrated graphics cards. When you install a dedicated gfx card it automatically disables the onboard graphics card. There is no option to disable the onboard gfx because it is already being overrided by the dedicated gfx card installed.

Xorg/ linux still detects that disabled card even though its not functional at all. Other distributions actually get it right. Ubuntu since warty has been getting it wrong ever since, it could be just debian in general.

This not for or about MULTIHEAD support.