Reign of the Supermen of Two Worlds: Rocket Men

Common for both Krypton-One and -Two is their exiling of criminals from their worlds, prior to their destruction. There were limited occasions where the Supermen encountered they crooks. Three criminals known to have been exiles of Krypton-One were Roz-Em, Dev-Em and Klax-Ar. Roz-Em had devised a scheme whereby he had his facial features operated on to alter his appearance into that matching Nim-El who was head of the Armory of Forbidden Weapons, which he intended to steal and use for ill-gotten gains. However, the real Nim-El along with his brother Jor-El happened to arrive at the same time and both captured Roz-Em, after which the authorities jettisoned him into outer space. Eventually reaching a solar system with a yellow sun, Roz-Em gained superpowers and sought to undermine his foes' son and nephew, Superboy. Pretending to be an adult Superman, he nearly succeeded until the Boy of Steel outwitted him, sending him to the Phantom Zone. However, a relative of Roz would later inflict more trouble upon Kal-El before being inspired to turn over a new leaf...

This exile and possible son of Roz-Em was the aforementioned Dev-Em, who was a juvenile delinquent who had plagued a young Kal-El and his parents, and was also sent into space. As was often the case, he too ended up on Earth-One, and sent Superboy into the Phantom Zone while taking his place. However, the "Knave of Krypton" as Dev-Em had a change of heart and, after repairing his relationship with the Boy of Steel, journeyed to the more advanced 30th century where his former foe often traveled to aid the Legion of Super-Heroes. There Dev-Em became a member of the Interstellar Counter-Intelligence Corps, and security the safety of the solar system of that era. As for Klax-Ar, his own exile rocket's journey led him to a planet where the radiation he was exposed to robbed him of superpowers yet left him after a clash with Superboy possessing a Superboy robot as his guardian. His counterpart apparently perished on Krypton-Two when it exploded, since there was no recorded incident of dangerous Atron rays being discovered there which was the reason that Klax on Krypton-One was sent into space.

From Krypton-Two, the only three recorded exiles were sent together, those being brothers U-Ban, Kizo and Mala... all of whom having been members of that world's Science Council. All three intended to usurp authority on their native world by threatening to remove the moisture from the atmosphere, until Jor-L unseats their plans. After being in suspended animation for several decades, they arrived on Earth-Two and immediately faced Superman who stood in their way of planetary conquest. After tricking all three into battling one another, the costumed Kal-L placed them in another rocket ship once more imprisoned. However, the trajectory of the craft ended up crashing into an asteroid. While U-ban and Kizo seek to retreat for relaxation, a vengeful Mala returns to Earth-Two to adopt both aliases of his hated adversary, leaving Superman to follow "Clark Kent's" activities. After being temporarily tricked into retreating to a counterfeit Earth of Mala's making, Superman creates another craft through which he lures the Evil Three Kryptonians, lacing its exterior with Kryptonite. Since prolonged exposure to this element is fatal for Kal-L and his people, it must be assumed that this was the end of all three brothers.

On Earth-One, the shrunken Bottled City of Kandor which Superman retrieve from Brainiac's space craft contained the descendent of Jor-El's twin brother Nim-El, Kal-El's cousin Don-El. And this Don-El was the Captain of the Superman Emergency Squad, a team of miniature Men of Steel that aided their namesake on occasion. Eventually assuming command of Kandor's citywide security, he aided his relative Van-Zee aka Nightwing, himself another imitator of Superman. Years later, Don-El's delusions made him think he was the real Superman, causing his cousin to hatch an elaborate scheme to awaken the captain by facing the hero's greatest adversaries.

As such, the counterparts of both Kryptons were Dev-Em and U-Ban, Roz-Em and Kizo, and Nim-El and Mala (with Nim's son like Mala once impersonating Superman). Many other Kryptonians were revealed as having survived including the residents of Kandor and Phantom Zone criminals. As for the shrunken residents of the Bottle City of Kandor from Krypton-One, there were the simulated denizens of the virtual Kandor within Power Girl's Symbioship, including Zor-L and Alura who existed in that form while their counterparts Zor-El and Alura were phantoms for years within the Survival Zone. The Dynamic Duo of Kandor-One, Nightwing and Flamebird had cosmic twins in the Crimson Avenger and Wing of Earth-Two.

Getting back to the faux-Men of Steel, we are just scratching the surface of those who attempted to assume the mantle of the greatest superhero to ever life. There would be others who would assume the Reign of Superman in his behalf. Who these would be will be learned of later...