In my CNC router I have 2 screws (M16x1.5) on X and 2 screws on Y axis.
X axis has 2 motors and two belts - so each leadscrew has separate motor and belt - one driver
Y axis has 2 motors and one common belt for both leadscrews and motors - one driver
the danger on separate motors like my X axis is when one of them stall and second motor doesn't, then it twists the axis (what happened to me once).
Since I rebuilt Y axis as described above I never had any problems with it.
The only thing i would improve is to designate one controller to one motor only, but like always the problem is the funds :) .
I can't assure you that is the proper arrangement but it works fine for me and I think results speak by themselves.