One early acknowledgment to the existence of parallel worlds, and counterparts on each, is that of Police Chief Parker.
During the teenage years of Earth-One's Clark Kent, Douglas Parker was the leading law enforcement officer of the then thriving burg of Smallville, and aided Superboy on several cases. In one instance, a Superboy from another unspecified world invaded Earth-One and plagued Chief Parker...thinking this man was one-in-the-same with his own variation of the chief. After being revived from his Red Kryptonite induced madness, the other Superboy returned to his own universe.
It was during this occasion that it was revealed there were other Parkers existing in the other universes. Since Earth-Two is the next closest reality to Earth-One, according to the accompanying diagram the Douglas Parker of that world was a criminal. This is logical as his own Smallville remained a rather small community, since the golden age Superman never became Superboy and hence did not attract notoriety to his hometown. The ape variant of Parker could be on the more bestial Earth-Three, while Miss Parker could be an officer on Earth-Four... she definitely looks like one of the military officers who encountered the silver age Captain Atom!
The more famous Parker ultimately retired and was brought back in a reunion show on Metropolis WMET-TV to honor the former Boy of Steel, and later was a member of the Smallville Chamber of Commerce.