Dual Z axis Steppers Please

Hi Claudio

I have several MKS SBASE boards and I have built a small cnc engraver (Spindle not Laser)
With a Cartesian dual z axis steppers. I have jumped the inputs to combine the E1 and Z axis together and connected a stepper to each controller. But I cant set the current on the tandem axis to match the current on the Z axis so one motor looses steps and jamms the z axis.
I know that GRBL dosen’t support dual Z steppers but is there a way to make it work.
Thank You.