I rode an Easy Motion (BH Industries, the Spanish conglomerate) with 2WD. Lots of fun, but, even with a sensor that adjusted the power when one wheel started to slip, didn't notice any advantage over 1WD. The real fun was when the torque sensor (apparently) got stuck and the bike flew up a fairly lone, relatively steep fire road. Also, I had a front hub motor with rear 8-speed derailleur; fun, but nothing special.
You would have to have both motors run off the same controller and both motors would have to be the same as well so the power output is identical on both. It could successfully be done but the need just isn't there. I've put my rear wheel moto bikes places only goats go. The actual need for the front wheel to be turning would be far less than 1% of the time.
Seems like the only time this would be an advantage would be really slippery terrain like snow or ice. Normally by the time the terrain is steep enough to benefit from 2wd, the weight is mostly on the rear.
Could be a benefit in packaging just being able to use 2 motors to increase power output though. Heat removal should improve at any given total power level.
I think that 2WD with separate dedicated systems is a good idea for an individual who can pedal minimally or not at all since they would be able to get home with the still operating one. I realize that if both systems are inoperative the individual is in trouble.
A much simpler way to achieve two wheel drive is to use a front hub motor and use your pedals and proper gearing to activate the rear wheel. I have over 2000 miles on this type of setup and it works just fine.