According to the
Character List for
The Rival the only other Met Star employee shown was J. Harvey Stark - Carpenter's right hand man.
That doesn't mean that L&C didn't bump into other Met Star reporters at press conferences, crime scenes, or "read" other Met Star's reporter's work (that would, of course, just be Clark, because I can't see Lois reading the Met Star, even to scope out the other paper). But this is the only one I can recall off hand.