For some reason a number of commercially built VFOs and kits used this type of variable capacitor. Usually one section had more plates than the other since the frequency of operation was often 160 meters for 160, 80, and sometimes 40 while the other section was for operation on 40 meters for 40, 20, 15, and 10 meters.
Glen, K9STH
Website: http://k9sth.com