Hi,
Atfer investigation, here is what I think : Legally, a Karmann Ghia is a 2+2 (2 front and 2 rear seats) as you could find on conformity document provided by VW (except for late convertible, only 2 seats legally).
Nevertheless, "2+2" doesn't exist for a french "carte grise", so sometimes "2+2" became "4" and sometimes it became only "2".
So, some of us have a KG with "carte grise" for 4 seats (like me), and others only 2.