Double concerto
A double concerto (Italian: Doppio concerto; German: Doppelkonzert) refers to two distinct variations on the concerto. Most often, it refers to a concerto featuring two performers, as opposed to the usual single performer, in the solo role. These two performers' instruments may be of the same type, as in Bach's, Concerto for Two Violins, or different, as in Brahms's Concerto for Violin, Cello and Orchestra.