In general, puffers don't get along well together. It's usually best to have only one per tank, and even then one must choose tankmates carefully because puffers can be somewhat bullish. Hope this helps!
If you do decide to get more than one puffer, make there there is plenty of plants and decor in the tank to make for good hiding spots. This way the puffers can each have their own territory and squabbles can be minimalized!