A lot of my PAO people are fictional characters or cartoon characters. I’m not yet done with my PAO system, but that’s the way it’s shaping up to be. So, 22 is Donald Duck.
Also, some of my PAO people are identified by roles rather than names - i.e. a dentist, for example. I just “see” a generic dentist when I get to that one.
I have aphantasia so I wouldn’t be able to actually “see” 100 different people in my head, but with my collection of PAO characters, I don’t even really need to visualize them. I just need to think of the archetype.