With its latest batch of reissues, including titles from Peabo Bryson and Roberta Flack, Tavares, and Nancy Wilson, Cherry Red's SoulMusic Records imprint can truly be said to cover a wide swath of the soulful spectrum. Duets have long been staples of great R&B. Marvin Gaye and Tammi Terrell, Roberta Flack and Donny Hathaway, James Ingram and Patti Austin, and Otis Redding and Carla Thomas - just to name a few in the pantheon - all proved that "it takes two." (That title, in fact, gave