Determined to have a career that's more Clay Aiken than Justin Guarini, ''American Idol'' runner-up Diana DeGarmo is rushing her first single into stores. It's not clear what tracks she'll be releasing, but the RCA Records website lists the release date as June 22. That's just one week after ''Idol'' winner Fantasia Barrino drops her first release, her already famous rendition of first-season ''Idol'' finalist Tamyra Gray's composition ''I Believe,'' also via RCA. Which means that the two singers will have a popularity contest all over again, this time measured on the singles chart. Both singers have also pledged to record albums as soon as possible, but they may not have time to do much recording before the ''Idol'' summer tour starts on July 14 in Salt Lake City.