Dorfman, Andru and Esposito conclude the Virus X storyline in Action 366 (Aug. 68).
Superman is found by some flame beings in the sun. He has been cured of Virus X, thanks to the white kryptonite thrown at him by the Bizarros. That killed the virus, and the sun healed his injuries.
Returning to Earth, he finds that no one realizes he has been gone, and that there are versions of himself fighting crime all over the place. He checks Kandor, and the Phantom Zone, but no one is missing.
The Supermen are actually his fellow Justice Leaguers, Batman, Flash, Green Lantern and Martian Manhunter and Aquaman, working alongside Supergirl.
This story was really highly regarded at the time.
Cary Bates and Kurt Schaffenberger introduce a pair of alien villains for Supergirl in this story.
Alpha and Beta are on a mission, and want one of the Stanhope students. They seal off the campus, which actually helps protect Supergirl’s identity, as her Linda robot is at class.
Not much is explained in this action-packed tale, which concludes next issue, but those bug eyes merited inclusion.