Comment # 7 on bug 1135237 from Stefan Dirsch

xrandr outputs are more or less identical. Outputs are named differently, but
this is to be expected for different X drivers. And in both cases the native
resolution is detected as 1080p. So that's fine.

It's the first time I hear a customer using Xorg with intel/modesetting as
(pseudo-) headless Xserver and then connecting via x11vnc(_ssh) instead
of just using VNC, but Ok. As you wish. 

I remember a customer using Xorg+dummy driver (really headless!) as virtual
Xserver and then just doing rendering and screenshottting the results. But for
this you could also use Xvfb ...