There are three nuns with the same first name embedded in the local Irascible Poverty Activists community. They've solved the problem by being Sister Name, Sister Shortened-Name, and Sister Initials.
Sister Initials is the one I was talking to today; she commented to me that, because both she and Sister Name were extremely combative personalities (they are), she'd decided to step away from certain projects that they were both involved in, in order to minimize "danger to by-standers."
I can't now help but imagine her ducking out of some kind of awkward Appellation Confrontation before it got ugly, allowing Sister Name to become the dominant nun in this arena.