i don't know what you have against Mozart, so if you just don't like pretty classical music, so be it (though it does mean i can't suggest the Clementi duets which are so charming and lovely).
Perhaps some Chabrier?
Musicology:
Prélude et Marche Française, for piano 4-hands
Year: 1888
Genre: Prelude / Fugue
Pr. Instrument: Piano 4-Hands
1.Prélude
2.Marche française
or some Rchamaninov maybe? i like the whole set but you could break it up/piece it out as needed
Musicology:
6 Duets for Piano 4-Hands, Op.11
Year: 1894
Genre: Other Keyboard
Pr. Instrument: Piano 4-Hands
1.Barcarolle
2.Scherzo
3.Russian Song
4.Valse
5.Romance
6.Slava! (Glory)
This is another rarely heard collection of gems from Rachmaninov's earlier years. Although not necessarily meant to be played as a set, it can be done so with good effect. Barcarolle (Moderato) in g minor. For once Rachmaninov actually writes a Barcarolle that sounds like a Barcarolle. Swaying rhythms accompany a lyric melody that incorporates typical swirling figuration to build to a climax. Scherzo (Allegro) in D major. This is a dazzling and brilliant virtuoso work, full of wit and rhythmic excitement. Thème Russe (Andantine cantabile) in b minor. Actually, a set of connected variations on an unidentified theme. It grows in intensity and volume up to the quiet reprise of the theme, which ends the piece. Not the most effective number of the collection. Valse (Tempo di valse) in A major. Similar in style to the earlier Valse for piano six hands, this is actually a suite of several continuous Waltzes in the traditional Chopinesque style. It is rhythmic and effective, if not particularly original. Romance (Andante con anima) in c minor. This is a melodious and lyrical Nocturne in a fairly straightforward late Romantic style; it is beautiful, simple and unaffected. Slava (Allegro moderato) in C major. An impressive work based on the same Old Russian liturgical chant as Mussorgsky used in Boris Godunov. The chant is subjected to continuing variations as it builds in intensity to a thunderous climax. An imposing and epic conclusion to the set.