Comment 5 for bug 752940

To answer your last question first, the reason Ubuntu tries to load both modules is that it has a different kernel module loading process, which was introduced to support both fastboot/upstart and flicker-free graphical boot/plymouth. But there are (obviously) some bugs in the module loading logic when multiple video cards are present, such as in your case.

Specifically, the presence of multiple kernel graphics drivers trips up the i915 kernel module driver and results in a gpu event to be triggered; however it is able to realize there isn't actually a serious problem, and it just resets the GPU and continues. However, that triggering is enough to fire up apport to prompt you to report a bug.

So, aside from the kernel module loading logic being a bit flimsy in this case, there isn't anything specifically broken that you need to worry about. The logic should perhaps be cleaned up better (we already have bugs filed to this end).