2 steppers-one axis?

I have a 3 axis stepper kit and just use the x and y axis and the 3rd
motor is not connected.
I was just wondering if I could use 2 steppers to drive one axis
making it possible to have more available power in an axis that is
almost direct drive? Would there be a problem with the x pulses not
being in sync with the z pulses,or are they?
Thanks in advance, before I start making brackets etc. Terry