For clarinet duets, I really enjoy the following:
Selected Duets (vol. 1 and vol. 2) - wide variety of both levels and styles
Lazarus Three Grand Artistic Duets - more challenging, but super fun to put together!
Ten Klezmer Duos (vol. 1 and vol. 2) by Mike Curtis - really well written and great introduction into the style
Sonata for Two Clarinets (B-flat and A) by Poulenc - standard and really fun to put together
Serenade No. 13 for two clarinet by Vincent Persichetti - I played this as an undergrad and I just think it is a really neat little piece
Toccata and Fugue in D Minor by Bach arr. Jonathan Russell - Bass clarinet duo. Need I say more
Double Concerto for bass clarinets by Jonathan Russell - while on a bass clarinet kick, this piece was one of my favorites to perform!
Black by Marc Mellits - this is a “bucket list” piece that I hope to perform sometime.
5 Huapangos by Mike Cutis - for B-flat clarinet and Bass clarinet, really fun and energetic piece to play
I know there are LOTS more and would welcome suggestions to add to my list! Contact me here!