That's all right. The MiG-21 has been in production for more than 40 years in about 15 different vervions. Only 3 of them were two-siters: MiG-21U, MiG-21US, MiG-21UM.

The MiG-21 cockpits were pretty much different. In black colour, then black and grey, then blue-green.
Radar displays were installed on combat versions.