The motors are completely identical; they are not very big and will run off exactly the same voltage (12v DC, wired in parallel). Even though the motors and voltage are identical, I'm sure the motor's outputs in terms of torque and rpm are still slightly different. For the motor going faster, I don't see why this is a problem; it will push the other motor along. For the motor going slower, it will be pulled along. Can bad things happen?

I would think the slower one would get hot and possibly overheat, but then I don't know shit about shit soooo...

this made me think of electrically powered trains, (real ones, not models).
I think two engines are commonly linked to provide more pulling power than a single engine.

Thanks, I decided to ask first because the project isn't urgent and screwing up my motors wouldn't be cool. I was almost certain it would be ok, I had the wiring and everything done. I'm actually using 3 motors now, I have 3 identical ones. I tested it with two and it was sufficient, but I want more power.

It will work fine.

It makes me wonder what happens when you externally drive a motor faster than it normally spins. Would it act like a generator and raise the voltage? Or would it act like a shorted motor, and resist any increase in speed?

I'll have to try this with legos...

Provided you don't do anything out of ordinary. [Insert emotion here]

I'll demand pictures!

It will indeed act as a generator. In fact to anser Hung also, train motors are driven individualy, sending equeal power to each. equal power may mean different voltage (actually pwm value, but dont mess) because of differences between motors. And when the train brakes, it's motors act actually as generators, returning power to the line, powering another train that is accelerating for example.

Edit: Spatula, a shorted motor acts like a generator also, the difference is that ,as it is shorted, the rotation implies high power delivered to the shorted wires hence the resistance to the movement. Here is a picture http://www.ecircuitcenter.com/Circui...otor_model.htm
I think the article explains it but I didn't read it