Today kicks off the annual Twin Days Festival in the town of Twinsburg, OH, which brings thousands of sets of multiples together to celebrate their siblings with games, parties, and parades. We're using the opportunity to pay homage to our favorite paired-up stars.
In addition to famous twins like Mary-Kate and Ashley Olsen, Benji and Joel Madden, and the Mowry sisters, there are a number of celebrities that you may not have known are part of a pair. Ashton Kutcher, Scarlett Johansson, Gisele Bündchen, and even Vin Diesel have twin siblings — and while some of their other halves keep a low profile, others have a place in show business as well. Click through now to see 15 stars that you didn't know had a double!