Both of those Angels are very similar looking. So it maybe a issue with fighting??? Not sure about that tho. But I always go by the rule if same color, shape or size of existing fish there is a chance of conflict.
I do have potter angel in my 90 gallon. He gets along with everyone except him and my female clown some time posture towards each other. But only around the clowns host pulsing Xenia. Otherwise very peaceful.