Rumor is that Mariah Carey is set to strut her stuff on the American Idol stage not once, not twice, but thrice. Fox News reports that it's a done deal for Mimi (the "good girl" diva) to join Bono, Brad Pitt, the Manning brothers and more on Idol Gives Back on April 9, and then return to the show the following week as a mentor, guest judge, and performer.Reps for the show tell PageSix.com that they will have several mentors this year, though they declined to confirm any names. The question is: Does this mean the Idol contestants are taking on Mimi classics? Because, boy, would we like to hear Amanda Overmyer sing "Vision of Love."