2 in B-flat major for violin and viola, K. 424, the second of the two Mozart wrote [see String Duo No.
1 (Mozart)] to complete Michael Haydn's set of six for the Archbishop Colloredo, was written in the summer of 1783.
As a whole, this duo blends in better with Haydn's four because the viola is more limited to providing harmony than in K. 423.
The set of six was presented as all Haydn's, and Colloredo was unable to "detect in them Mozart's obvious workmanship.
"[2] The Austrian composer Gerhard Präsent has made an arrangement for string trio (2 violins & violoncello) in 2012, regularly performed by the ALEA Ensemble.