If imitation truly is the sincerest form of flattery, then Trey Songz's hit ''Open the Closet'' should have R. Kelly blushing. So taken was the R&B newcomer with the first chapter of Kelly's popular ''Trapped in the Closet'' musical soap opera that he recorded an ''answer'' track. The revamped version finds the 20-year-old Virginia native uncannily mimicking his idol who declined to comment as he offers another vantage point on Kelly's adulterous plotline. ''I listened to [the original]intensely,'' says Songz (a.k.a. Tremaine Neverson), whose debut album, I Gotta Make It, drops July 26 on Songbook/Atlantic. ''Then I sat down and recorded it myself. It took about 45 minutes.'' Circulated on several underground mixtapes, the tune started receiving major radio play from coast to coast. ''That bugged me the hell out!'' he says. ''It's a thing I did for fun that got more shine than it was meant to get.''