No two puffers are compatible. There should never be more than one puffer in a set up. That's the written rule. Of course I've seen it done and you'll come to find out in this hobby it's a trail and error kind of thing. You have to know your fish, how aggressive it is how territorial he is.
I wouldn't suggest it. Definitly not in a 50 gallon tank. I had a Mappa Puffer in my 125 that I soon had to return to the store b/c it was too big (10 inches). You need at least a 100 gallon tank to house a dog face or porcupine.