Ah I see, thank you for your reply! I’ll check it out then, if they have both the tangs of similar size at the same time!I've had a purple for years now. I have added fish with no aggression. But I have not added a tang with him.
I have added different wrasse, blenny, royal Gramma. Never looked twice at them.
I recently added 2 bellus angels but sumped the tang before adding. Waited a couple weeks before putting the tang back in the main. No issues with that either.
With Zebrasoma tangs, IMO, it's a roll of the dice. Again, IMO, best to add at the same time.