Here are all duet pieces.  Two players - no more, no less.  (MS = MuseScore source file.)

 

Click on item to download or view

Bass Clarinet and Piano MS MP3 PDF
Clarinet and Piano MS MP3 PDF
Viola and Piano MS MP3 PDF
Flute and Piano Number 1 MS MP3 PDF
Flute and Piano Number 2 MS MP3 PDF
Flute and Piano Number 3 MS MP3 PDF
Prelude for Trumpet and Piano Number 1 MS MP3 PDF
Prelude for Trumpet and Piano Number 2 MS MP3 PDF
Prelude for Trumpet and Piano Number 3 MS MP3 PDF
Tres Tria Caecus Mus Muris for Piano and French Horn MS MP3 PDF