Guests will never see two of the same character at once.
And I mean ever. That's because there's only one of each character. Cast members carry a guide every day that gives them all the necessary information for their park that day, including park hours, attraction times, character showings, and all necessary phone numbers. Want to know where Cinderella will be at 3 p.m.? Ask a cast member. If she isn't in that particular park, the cast member will be able to tell you where to find her.