Stars in Halloween Costumes

Brandi Pettijohn/FilmMagic

Haylie and Hilary Duff were a blast from the past at Airparty Hollywood's benefit for the Trevor Project in L.A. Haylie went as an '80s aerobics instructor; Hilary dressed as a gypsy.

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Holiday 2007

Stars in Halloween Costumes

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Haylie and Hilary Duff

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