Motor shield R2 and CD-Rom stepper

Hello,

I have a problem with my stepper - im using one rated for 12/24V and second one salvaged from old CD drive.
Problem is, that when its powered from USB, it have not enough power to turn big one, when powered from 12V, its attepting to burn small stepper even when he is idle.

Is there a way to attache those 2 motors at once to single shielded arduino uno ? Like to reduce current for one stepper or smthing ?

If they are connected bipolar the only thing I can suggest is
resistors in series with the windings of the smaller motor.