Action Comics #165

Clark is assigned to literally unmask the new Crime Czar. Another news story unfolds, when a spaceship evidently hailing from Mercury lands in Metropolis. From it emerges an almost exact duplicate of Superman, calling himself Krag. He proves to possess many of Superman's powers, including flight and super-strength. But Krag aligns himself with criminals, and he later gains an audience with the Crime Czar. Snatching off the mask, he is revealed to be the Mayor's assistant, Fleming. At this point Superman reveals that Krag was a robot which he operated remotely.