The two seat Spitfires were modified by Vickers after the war to provide trainers for the Irish Air Corps and Indian AF.
There were several incidents of Spitfires flying "two-up" during the war, with two stuffed into the cockpit - Tony Bartley mentions doing thus in his autobiography. Then there was Margaret Horton, accidentally carried aloft draped over the tail plane of Spitfire
VB AB910; still flying with the BBMF! Margaret died just a few years ago, as did her pilot, F/L Neil Cox.