Yep I found the thread thanks
Unfortunately the abilities file doesn't list a use for the second value for combat to hit offense/defense so my guess is right now it doesn't do anything. But it shouldn't be impossible for MM to modify the search routine that looks for combat bonuses to adapt it to something like the one used for extra movement.
I hadn't noticed that Fleet and Individual experience didn't stack
Are they planning to fix that? They make it pretty clear in the documentation that it should.