Instrumental Duet Instrumental Duet,Viola,Violin - Level 3 - Digital Download SKU: A0.965298 Composed by Boyd E. Gibson. Contemporary,Instructional,Standards. Score and parts. 28 pages. Boyd Eugene Gibson #5011759. Published by Boyd Eugene Gibson (A0.965298). This set of 24 canons is set as duos for violin and viola where both parts are equal.