Military Aviation

Looking for information: I'm working on a video about the MiG-17 and would appreciate some help from those who are knowledgeable about Soviet aircraft history. I have a question regarding the gun camera on the Soviet MiG-17. The MiG-17PF, as well as other versions of this fighter, had a built-in camera, the S-13, in the nose (Picture #1). Sometimes, and there are many pictures proving this, the MiG-17 was equipped with the FKP-2 gun camera installed right in the cockpit (Picture #2).

My question is, why did they install a gun camera in the cockpit when they already had a built-in gun camera?

The only possible answer I've found is that the FKP was sometimes installed on MiG-15 trainers, specifically those equipped with training radars. The FKP in the second cockpit could "capture" the radar marks/information. Were the single-seated MiG-17PF equipped with FKP for the same reason? And does that mean they carried two gun cameras (one in the cockpit, one in the nose)?