Mary-Kate and Ashley Olsen [1] made a rare appearance at the Met Gala on Monday. The sisters, who usually step out for fashion's big night [2], hit the red carpet at the Metropolitan Museum of Art in NYC in coordinating ensembles. They then let loose and danced the night away together at Katy Perry [3]'s afterparty at the Boom Boom Room at the Standard Hotel. This also isn't the first time we've seen them in recent weeks. The sisters attended another (more relaxed) gala [4] with Mary-Kate's husband, Olivier Sarkozy [5], in April.
