It's every celebrity's worst fear -- showing up on the red carpet in the same dress as someone else -- but this time, it was intentional.

Sigourney Weaver and Jamie Lee Curtis went to the "You Again" premiere last night in the same asymmetrical turquoise dress -- mirroring a scene in the movie where they accidentally dress alike to a wedding rehearsal dinner.

Check out more pics of Kristen Bell (wearing Valentino), Odette Yustman and the one and only Betty White from the red carpet, then let us know ...