25 Easy To Middle-Grade Duets From The Last Four Centuries. The flute duet has been a favourite combination for centuries resulting in many fine compositions and arrangements, not least of which were of many operatic overtures and arias - the pop music of the day - making these 'hits? available for people to play in their own home long before the gramophone was invented. 'Bühne Frei!? or 'Curtain …