Les Plaintes de la Jeune Fille by F.Schubert for Flute and piano duet.
With downloadable mp3 for audio help.
Pages: 9 pages (7 pages flute and piano score, 2 pages flute solo) 2:19 min.

Marche Turque theme by W.A.Mozart for Piano duet 4 hands. 2 pages.

Deutschlandlied ("Song of Germany", also known as "Das Lied der Deutschen" or "The Song of the Germans"), was conducted by Joseph Haydn in 1797.
Here is a piano duet 4-hands arrangement, 5 pages (3 pages both hands, 1 page prima, 1 page seconda) with downloadable mp3 for audio help.

Tagus an easy piano duet 4-hands composed around 1820 by Hector Berlioz (1803-1869).
Pages: 2 pages both hands, 1 page prima, 1 page seconda, 1:15 min, with downloadable mp3 for audio help.

A bergerette, or shepherdess' air, is a form of early rustic French song.
Here is a known melody easy piano duet 4-hands composed in 18th century by the French composer Pierre-Alexandre Monsigny (1729-1817). 
Pages: 3 pages both hands, 1 page prima, 1 page seconda, 1:22 min, with downloadable mp3 for audio help.