Duettino
A duettino is an unpretentious duet with a concise form. Wolfgang Amadeus Mozart offers several well-known examples of the type, including "La ci darem la mano" from Don Giovanni and "Duettino No. 3" from La clemenza di Tito, a song only twenty-four measures long. He also described "Via resti servita" in The Marriage of Figaro as a duettino.