[apalrd]

For smaller motors, they will be just fine under a single control (and this is legal now, finally).

Example:
The combined stall current of 2x window motors on a Talon is well below the continuous current spec of the Talon and on a 40a breaker it will be impossible to trip (the PTC in the motors will trip first). We wired our 2011 practice robot using 1x Victor, using 2x Victors and a Y-cable on the competition bot.

Don't put two large motors like CIM's on a speed controller and expect it to live, though (although the 40a breaker *should* trip first).

Y-cables are also highly recommended whenever two motors do the same thing. Our 2012 robot in it's final state had 16 speed controllers (14x Victor 2x Vex) and 2 servos on a single digital module and sidecar, all made possible with Y-cables.