I'm not a developer myself, I'm just trying to guess what the problem can be so I can point it to the right person.
Therefore, it would be great if you could try to boot the live CD with only 1 card at a time and see if both cards works fine when the other one isn't installed. I'm not sure that the live CD can handle this unusual setup, i.e. having 2 different cards.
When you try this, please attach xorg.conf and Xorg.0.log and report back the results of your test.
I'm not a developer myself, I'm just trying to guess what the problem can be so I can point it to the right person.
Therefore, it would be great if you could try to boot the live CD with only 1 card at a time and see if both cards works fine when the other one isn't installed. I'm not sure that the live CD can handle this unusual setup, i.e. having 2 different cards.
When you try this, please attach xorg.conf and Xorg.0.log and report back the results of your test.
Thanks!