RE: 2.2 class rules- kinda hazy....
Lots of people use dual motor in regular 2.2 class. Its called a motor on axle set up where each axle has its own motor. In fact, I'm pretty sure the whole rock crawling segment started by use of MOA axles from Clod Busters
If youre talking about twin motors driving one gearbox, thats another story. Mainly, it would be way too much weight up on the chassis to have any advantage over a single motor or motor on axle setup.