Duo for Violin & Viola in G,K 423 Duo For Violin And Viola in G,K.423 Duo for Violin & Viola in B flat,K 424 Duo for violin and viola in G major, K423 Duo for violin and viola in G major, KV 423 Duos for violin & viola Duo for violin and viola in B flat major, KV 424 Duo for violin and violoncello