Double Concerto in B flat major
ed. Anton Geerb
The present concerto for two violins lack the viola part. This is probably due to it being written for cardinal Pietro Ottoboni's ensemble, where according to financial records the violas were often absent. Rhythmically there are many surprising shifts and thematically Valentini delights in playing around the interval of the tritone - 'the devil in music'.
The source is item 65 in the Manchester Concerto Partbooks.