Can you breed two different breeds of rabbit?

If you mean the domestic breeds then yes. They are all a part of the same species, Oryctolagus cuniculus (the European Rabbit),and thus can interbreed and produce viable offspring, this is also true of interbreeding wild European rabbits and domestic ones. But it probably would not work if you tried two cross two different species of wild rabbits (or other lagomorphs) because, in part they have different gene counts. So you could not cross an eastern cottontail (Sylvilagus floridanus) with your pet rabbit, but you could cross a Rex and an English Spot, since they are just two breeds of domestic rabbit.