In 1953's Action Comics #182 and once more in 1966's Superman #189, two Supermen returned to their home worlds...or were they?
Superman was informed of a planet and its artificial red sun entering Earth-One's solar system, on a collision course with his adopted world unless he intervenes! His counterpart is also notified of a large globe which entered Earth-Two's solar system, only it was placed in a stationary orbit separate from his adopted planet.
Flying to these strange globes, the Men of Steel notice how similar they appear... to Krypton! Upon further investigation, they quickly ascertain that due to the red sun radiation/higher gravitational pull they have been left powerless!
Still able to survey their surroundings thanks to resident modes of transport in the form of a hover-car and jet-pack, the Men of Tomorrow find men of their worlds' past... and strange towers the prove instrumental in determining the nature of these strange spheres!
The costumed Mr Kents find themselves perceived as threats by the local Kryptonians, and these locals aren't exactly what the seem at first. Hence the problems that ensue...
Borrowing technology around them, Kal-El unleashes a deluge of hailstorms upon the city's citizens, and Kal-L develops a tank to show his superiority toward his fellowmen who seek to enslave humanity!?! In each case, disaster results no doubt do reliance on their superhuman abilities throughout their lives on Earth.
During the course of this odd adventure, our heroes' learn the origin of these artificial worlds. It turns out that invading forces from space attacked the Kryptons in both universes, and the Kryptonians decided to create replicas that would fend off further extra-terrestrial threats in the future.
And, in fact, that is what happened when Krypton-1's twin wiped out just such a fleet of ships attacking it using bobby-traps, while on Krypton-2's twin a few of the invaders survived on the planet.
So it turned out that the humanoids whom Kal-El met were actually android duplicates of several Kryptonians including his parents Jor-El and Lara, his time lost sweetheart actress Lyla Lerrol, and a few scientists. As for those individuals whom Kal-L encountered, they were actually the former invaders pretending to by his people.
After further mechanisms are activated, Krypton-II is consumed inside the replica red sun which disappears, while Krypton-2-II remains in tact in Earth-Two's solar system! This correlates to the continued existence of the Krypton of Earth-One's universe through the remaining decades after its cosmic twin had been decimated.
And, in the end, we see a scowling Clark contemplates on one dimensional plane of his lost love Lyla, and on another how he was almost absolutely defeated by cunning foes!