Yes, you can have two drivers connected to a single axis. If you want the two drivers/motors to work as a single, more concerted pair, then I would suggest connecting the two drivers to a single step pulse and direction signal.
That is to say:
driver 1 and driver 2 have wires connecting from the CP terminals of the drivers to a single step terminal on the interface board (USB or parallel breakout board), and the CW terminals of the drivers connected to a single direction terminal on the interface board.
If the motors need to spin in the opposite directions, simply reverse one of the the motor A B coil connections (i.e. wires that would go to A+ and A- is connected to the B+ and B-, and the same with the B+ and B- to the A+ and A-). You can alternatively resolve this mechanically if desired.
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Can I have two motors and drivers on a single axis?