Almost 18, MARY-KATE, left, and ASHLEY OLSEN are already fielding grownup offers: they turned down an invitation to pose for Hustler magazine. But as the queens of tweens prepare to open their first feature film, New York Minute, next month, they would like us to identify them as individuals. "If someone comes up to me and says, 'Hey, are you the Olsen twins?' I'm like, 'No,'" rebel and recent brunet Mary-Kate told Premiere. "It's rude." This doesn't signify a newfound desire to be detwinned, however; they're starting at the same university in September.