Bah...I think you are right Red....my mistake
Lol...I'm fairly sure, though. Whenever they chase you, the Prefect theme plays, and in the ide file, one of them is listed as a PREFECT while the other is listed as a STUDENT.
It's likely the same trick as the scripted spawns (girls in pajamas, boys in gym uniforms, elders scolding students, etc.) and the industrial townsfolk spawning.