My motor has 0.67A per Phase but on microstepping driver I can choose between 0.63A or 0.84A. Does it really makes a difference?

I have runned it so far on 0.84 and I have noticed that motor gets very hot but I guess less than 80 degrees is fine?

Another thing... this microstepping controller also supports 1.5A and since I need on 2 axis parallel motion thought of connecting two 0.67A/Phase motors parallel on the same controller. I tested it right now and it works but is there something very wrong with it/with consequences?