There were historical two seat trainer Spitfires, field modded from single seat versions by both Russia and the RAF. There were lots of historical two seat trainer Spits made after the war.* Is this one a mod of a single seat version? And if it is, if they modded it the same way the historical trainer was made, what's the diff? It's probably just one of the post war two seat trainers.
*"Spitfire. The History.", Morgan and Shacklaldy, ISBN0-946219-48-6, pages 303 and 378.