what she means:
in that one episode of sonny with a chance, when sonny created a fake club called "the basement", she told tawni that chad still believed miley and hannah were two different people. this means that both shows existed in the same universe during the same time period. when selena gomez guest-starred in one episode, she played herself, yet she portrayed hannah's archenemy mikayla on hannah montana. lets also recall that hannah and alex russo met on the S.S. TIPTON during the crossover "wizards on deck with hannah montana". so is selena really leading not a double, but a TRIPLE life? and more importantly, what is her real identity? selena, mikayla, or alex?