First: A duet on two Gibson mandocellos, K1 and K4, both from 1924. Both Lloyd Loar period with truss rod. The K4 has a virzi inside.
Second: A duet on a Collings OM-1 guitar and on a 1924 Gibson K4 mandocello. The K4 is Lloyd Loar period and has a virzi inside.
Notation and tablature of the melody part as played by the 1924 Gibson K4 mandocello in the videos.It is in the key of G!