1 in G major for violin and viola, K. 423 was the first of two duos that Wolfgang Amadeus Mozart wrote to complete Michael Haydn's set of six for the Archbishop Colloredo.
The American musicologist H. C. Robbins Landon noted of the duo that Mozart used the knowledge he gained in writing his String Quartet in G major, K. 387,[2] the finale of which was in turn influenced by Haydn's Symphony No.
[citation needed] The set of six duos was presented as having all been composed by Haydn, and Colloredo was unable to "detect in them Mozart's obvious workmanship".
In 2012, the Austrian composer Gerhard Präsent made an arrangement for string trio (two violins and violoncello), which has been performed several times by the ALEA Ensemble.
The Hungaroton label has a 2-CD set of the Mozart and Haydn duos with Barnabas Kelemen and Katalin Kokas.