If you have more than one person creating segments chances are there is some duplication and/or label collisions Either the same exact segment is labeled differently, or different segments are labeled the same.
What would be great is that when someone is trying to save a segment, and a query is performed to see if that criteria already exists to allow a user to copy their own instance of it, or use the shared one.
Alternatively provide admin's the ability to find duplicates and remove them.