It means that some was created when Your account wasn't tied to SEN account (all zeroes) and some are restricted to NPAID. UN i CID can be seen only in hex editor as they are not wrote in any showing meta data in SFO. I can't remember on which offsets but they are easy to find, especially in higher user numbers than 00h or 01h.
I logged into PSN couple of times only and i created a PSN account though i never used it after that. I suspect that Account ID 36 31 37 33 38 61 62 31 65 63 30 34 36 65 36 65 is related to SEN account. Some of the game saves were created after creating PSN account while most are before that.
But why does it matter? Whether its 00 00 ... or 36 31 .... or any number. These save files should be recognized. But i cannot use any of the save files. Neither 00 00 .... nor the other one.
By the way, my saved PSN account is now deleted when i did file system restore. I cannot create a login PSN because i am on 4.84. When i go to Signup/login, it says to update my firmware.