Great violin/violin and violin/cello duet recordings:
19. Duets for Two Violins, Itzhak Perlman and Pinchas Zuckerman
This is just a wonderful album. Highly recommended for those who love the violin.
20. Duets for violin/cello, Mozart, and Beethoven, Boris Abramov & Carmine Miranda, a bit too compressed but still nice
20. Viola - I used to be the first viola in an orchestra - everyone's least favorite instrument, but Harold in Italy by Berlioz is great (supposedly commisioned by Paganini):
20.1 Nobuko Imai, Sir Colin Davis & London Symphony Orchestra - my favorite
20.2 Gérard Caussé, John Eliot Gardiner & Orchestre Révolutionnaire et Romantique - an odd version
20.3 Donald McInnes, Leonard Bernstein & Orchestre national de France, flamboyant