1 Stepper but w/ 2 lead screws is what you really want. 2 steppers has a chance to become out of sync.Yup, i gotta find a way to repair them. I can't justify another 16h print + filament lol..
There are some that did a dual Z lead screw mod. 2 z steppers working in tandem.
I'll grab a pic from one of my printers later on so show what I mean exactly.