LOS ANGELES (TheWrap.com) – Justin's going to be one busy little Bieber on February 9. "Baby" singer Justin Bieber will do double duty on "Saturday Night Live" for its February 9 episode, serving as both host and musical guest, NBC said Wednesday. Bieber, who's currently thrilling tweeners everywhere on his Believe World Tour, has appeared on the late-night show in the past, appearing in a skit opposite "SNL" alum Dana Carvey's Church Lady character in a February 2011 episode. …