Just be careful and very attentive. I'll relay a personal story here:
I have a 4 year old Manouria emys phayrei that I raised from an egg. Then last year I hatched another one. They lived separately for a year, and this spring I got the bright idea to put them outside in the same habitat. The size difference was great. The pen they were put in was triangular shaped and the tortoises wanted to both sleep in the very point of the triangle. One morning I brought them both out to feed them. The bigger one had spent the night sitting on top of the smaller one. The smaller tortoise, now a year old, was flatter than a pancake. I'm not exaggerating. Spending the whole night under the weight of the larger tortoise caused the smaller, more pliable tortoise to become flattened. It took about a week for the poor baby to "fluff" back up. I can't imagine how hard it must have been for that baby to breathe with flattened lungs. Needless to say, they now each have their own habitat.