MOSRITE manufactured the JOE MAPHIS DOUBLENECK (also known as the Mosrite MARK XVIII) between 1965 and 1969. It was similar to the Joe Maphis single neck model except it had an extra 12 string neck. A 4 string bass neck was also an option on this model as was a mandolin neck.
Mosrite promotional material described the Joe Maphis Double neck as follows (in 1965):
The new JOE MAPHIS SOLID BODY ELECTRIC DOUBLE NECK guitar, by MOSRITE. This guitar is truly a musical masterpiece and boasts such newer features as two slender speed necks, adjustable hi-fi pickups, a complete fuller range of high and lows, more drive and response. Quality and craftsmanship make the JOE MAPHIS DOUBLE NECK guitar the unrivaled KING OF STRINGS , for which it was named. This six and twelve string guitar is designed with the precision of a flight into orbit. Price $689.00 - case $60.00 Metallic finishes of pearl white and metallic blue an additional $30.00.