There are always certain risks when keeping more than one rabbit of any sex in one cage. Sometimes 2 girls or 2 boys won't get along...sometimes a boy and a girl won't get along (make sure they are fixed!). But most often things should be ok if you let the rabbits get used to each other. One trick is to keep the rabbits seperated at first in their own cages...then put the cages side by side. This way the rabbits know the other one is there, they can see and smell them while getting used to them.
Then after a few weeks, put the two rabbits together and see what happens. If they get along, then great! If not, they might have to help seperately. And if you want to keep two rabbits in one cage, make sure its big enough.