So a Pit Fiend has a neat little thing called a fear aura. Essentially if you start in it, you have to make a save or be frightened. We know from a related question that the rules for combining effects would require a creature subjected to this aura from two Pit Fiends would only roll one save. But the Fear Aura also says:
If a creature's saving throw is successful, the creature is immune to the pit fiend's Fear Aura for the next 24 hours."
Does this mean a creature that successfully passes its saving throw would be immune to the aura from other pit friends, too?