Curses! Whole post just disappeared...
We have the Great Scott ragtime album for violin (not duet). Sheet music for solo violin part, plus CD with tuning sounds and separate solo violin and backing tracks for each piece.
There are 4 albums of short duets in 1st, 2nd, 3rd and 1-3rd positions. Also the Brahms and the Bach "double" concertos. And a selection of Veracini sonatas for Violin (or other instrument) and harpsichord...
Music Minus One violin albums/sheet musicI ordered our one off Amazon, but I know a number of sheet music online shops carry them.
There was a whole MM1
thread a while back on the forums.
There's another thing called "Duets for One" which works in a similar way, but I haven't seen any of their products.