you can do both but not on the same day. if your gym doesn't allow you to do backsquat, then just go do front squat lo. highly recommended for athletics. are you an athletic?

p.s. i squat 2 plates, but front squat only 160lbs :I so yeah, not being able to lift what you are suppose to could be quite a blow.

p.p.s poor form/stretching/warmups = injury. go figure why you get hamstring injury.