If games have different characters with significantly different storylines (especially fighters), then you should have multiple endings corresponding to the events in the game.

Tiny differences in endings, like Chrono Trigger's changes depending on how many cats you own, are small Easter eggs and I think those are okay.

Fake endings, where you get a not-so-good ending for partially completing the game or completing it on a lower level, are acceptable.

Multiple endings for the sake of multiple endings are just plain stupid. Admittedly, most of the Chrono Trigger endings were good. Not everyone can be CT, though.