Malcolm:
You raise an interesting point. Albeit being CAA registered as a Spitfire IX, and manufactured as a single-seat aircraft, certainly when I saw this aircraft at Strathallan in 1973 it was the two-seat trainer version Tr.9 and remained so until conversion back to single-seat configuration in 1992 whilst registered as N8R.
Separate profiles to show both versions could be achieved with 159, MJ772 and G-AVAV shown as two seats (Tr.9) and D-FMKN as a single seat (IX), but N8R existed in both versions although all the site photographs of N8R are the single-seat version.
An Admin comment could be an alternative solution. Insofar as the c/n is concerned, I favour CBAF 7269.
Peter