Although amazon puffers are more peaceful than some, I wouldn't recommend this mix. Butterflies are a generally sedate species.
Also, as they obviously come from different parts of the world, they would never encounter each other in the wild, so you just never know what might happen.
I know people are going to think 'wll you could say that about most community fish', but I have always thought that many problems with fin nipping, aggression etc could be partly due to the fish not being natural 'neighbours'
Yo momma so ugly, she makes my frogfish look cute