The motors we usually use are called steppers, not servos, which are a different thing completely.
Connecting two of the drivers in parallel seems like a bad idea, but I'm not sure it wouldn't work. You're relying on the outputs to switch on/off at exactly the same time. If they don't, motor performance would probably be poor.
If you need to drive a higher current motor there are stepper driver modules available that will do a much better job than the little pololu modules for just a few $ more.
Ultra MegaMax Dominator 3D printer: [
drmrehorst.blogspot.com]
