When they got to the mall, Karyn concentrated on the fourth choice, the one that made people think that she was Sarah.
Jon blinked, and looked at her. "Woah...I'm getting a double image..." He blinked again. "Better...for a second there..I saw both of you..."
Meanwhile, as Karyn had figured out, the real Sarah was in the mall. As soon as Karyn made the change, everyone thought Karyn was the real Sarah...which meant the real Sarah thought Karyn was Sarah...And Sarah thought she was...