This Duo for two flutes was published in 1807 by Simrock in Bonn. An unidentified arranger made a compilation of the Piano Sonata in two movements (K 547a), the third movement of the Duo in G for Violin and Viola (K 423) and the last movement of the Sonata for Piano and Violin (K 547). It was a way of acquainting flautists with other works by Mozart. Even lengthy excerpts from operas were arranged for one or two instruments. Arrangements could be a lucrative business, which is why composers often undertook the task themselves. Mozart, for example, made an arrangement of his opera Die Entführung aus dem Serail for wind octet
Difficulty level, roughly compared to ABRSM exam grades. 0 is beginner, 9 is advanced (beyond grade 8).