Cate Blanchett is one of many celebrities who has re-worn outfits on the red carpet.Mike Marsland/Mike Marsland/WireImage/Getty Images ; Matteo Chinellato/NurPhoto/Getty ImagesRe-wearing outfits is popular at red-carpet events and in everyday life.Christian Siriano wants people to embrace repeating outfits they love.He recommends accessorizing and styling looks differently and disregarding fashion "rules."It's official: Re-wearing outfits is in.While "outfit repeater" was once an insult hurled at Hilary Duff's character on Disney Channel's "Lizzie McGuire," re-wearing items of clothing has even become a red-carpet trend with celebrities including Emma Stone, Cate Blanchett, and even Kate Middleton recycling their looks from years past.Just ask Christian Siriano, who's dressed numerous celebrities for red-carpet occasions.