I noticed WQSR and WHLK frequently had the same songs at roughly the same time. I always remember Charlotte's Lake being different, though I wouldn’t be surprised if it had the same playlist as the other stations in the same format. If you were to randomize those songs, even with the same categories, you theoretically wouldn’t hit the exact same order on two different computers.
One of the more interesting implementations of Jack FM that I once heard was KSPQ 93.9 out of West Plains, MO. It puts a decent signal, at least on a car radio, into the Branson area. It ran its local classic rock format in morning and afternoon drive and the satellite Jack FM the other dayparts. It used to refer to itself as “Q94 & Jack FM.” Of course, one could reasonably argue that interesting approach didn’t work, and the station is back to being ”Classic Rock Q94.” Not sure what it airs in middays and overnights, but it picked up Alice Cooper's syndicated show for the night shift. It hasn’t mentioned “Jack FM” in several years.