Earlier this month, I interviewed Rachel Bilson about her biggest beauty regret. I love Bilson, having been a fan of The O.C. as well as Hart of Dixie (RIP). But because I hadn't had coffee yet or because I had a serious mental lapse, I called her Leighton Meester to all my colleagues. I know they're not the same person, but they were both huge teen stars. Of course I was also a huge fan of Meester in Gossip Girl. For some reason, I totally mixed them up in my head. That got me thinking about all the other celebrities who look so much alike it's scary. Some have the same hair, others have totally different hair but the same facial features. And one pair of celebs is even 50 years apart! But seeing these duos is like seeing double.