There's probably a German word for it, like "komikalreadyhastreadun" or something.

That familiar feeling, where I thought this was going to be a new book to me, and about three pages in, well...from 1982, DC Comics Presents #50, "When You Wish Upon a Planetoid!" Written by Dan Mishkin and Gary Cohn, art by Curt Swan and Kurt Shaffenberger. Which was reprinted in the digest Best of DC #35, so yeah.

On one of his space missions, Superman hustles to correct the path of a rogue planetoid, so he can get back to earth in time to do the GBS newscast as Clark Kent. Supes idly wishes he could be both Superman and Clark Kent, so they would both be free to live without worrying about the other; but embedded in the planetoid is the unseen Miracle Machine, from a bunch of old issues of Legion of Super-Heroes: think Cosmic Cube, in a very retro package.

The next day, Clark reports from a United Nations Superman Day shindig, that Superman no-shows. Back at the Planet, Perry White lectures Clark for his somewhat scolding piece, since Superman had been busy stopping a flood. Still, Clark feels like the Man of Steel needed to spend some time with the people he was protecting; and honestly there was always going to be some disaster somewhere. But, over the teletype, news breaks of the Atomic Skull attacking S.T.A.R. Labs, and Clark dashes into a storeroom...for why, again?

I want to say Atomic Skull was created, to maybe be a bad guy Superman couldn't stomp all over with one hand tied behind his cape, to give at least the pretense of a fight? His look would've been pretty retro even at the time, but if memory serves, that too was intentional: he had patterned himself after old movie serial villains. I'd kind of like to see that moustache-twirling characterazation paired up with his 90's roid-rage villain look. Anyway, the Skull manages to escape, by shooting down the Planet's "Flying Newsroom" helicopter and Lois Lane: Superman saves her, but with a lecture that if it came down to always just saving one reckless troublemaker, he might not always be there for her...! Back at the Planet, Supes is also short with Lana, who confides in Clark at least he stayed sweet "--unlike that self-important super-sourpuss!" Superman continues round-the-clock jobs, but isn't there to stop the Atomic Skull hitting a Detroit S.T.A.R. Labs.

Researching the Skull's past, Clark puts together what his next targets will probably be, while Lois wonders what's up with Superman. Clark recalls him changing after a space mission...wait, how would he know that? He then researches old Superman stories, that he had written, but had no recollection of. (That's why you need a blog! Jar the memory.) He also gets a phone call from Batm--er, Bruce--asking him to cover Gotham for a few days. Clark has no idea what he's talking about; which Bruce merely takes as cover, that he wasn't able to speak freely right then. I have to wonder if Gotham got looted to the ground that weekend...Then, there's a fun anniversary two-page spread of the 65 guest-stars in the title up to that point, including He-Man and Battle Cat!

Clark had realized something was amiss, but wasn't able to put his finger on it, until he awakens from a dream about that space mission, and realizes his glasses don't seem to affect his vision any. Taking them off, he finally makes the connection, and the next day at work races to Jimmy Olsen, to have him use his signal watch to summon Superman. (An idea that I think had been falling by the wayside at this point.) Clark takes Superman aside to confront him, about his impatience and irritation, and something they previously missed because of the Miracle Machine: Superman had stopped the planetoid from crashing into a planet, but it was still going to hit the planet's moon. Running the numbers again in his head, Superman realizes Clark was right, and Clark tells him, they're the same person. But, before Superman can head back into space, Jimmy busts in (not seeing Clark put his glasses back on) because the Atomic Skull was going to cause a nuclear meltdown in a reactor in California. Superman can't let billions die in space, so that has to come first; but Clark tells him to drop him off in California, he'll stop the Skull!

At a S.T.A.R. earthquake research lab, Clark puts his news-know-how to work: the reactor had been set up with elaborate anti-earthquake safety measures. So, by setting up a tremor at the reactor (as of course, any earthquake research lab could do...) the Skull gets swamped in anti-radiation foam...which, honestly, probably should've gone off the moment he entered the building. After stopping the planetoid, Superman returns, and he and Clark make a visit to the Kent house in Smallville: there was still the secret tunnel, and Superboy's old lab. Superman doesn't think Clark is lying, he just can't remember ever being Clark Kent. The kitchen doesn't do it either, but visiting the graves of Ma and Pa Kent does the trick, and Superman and Clark are reunited, with maybe a little more appreciation for each other. 

I don't know if they ever did this in the post-Crisis 'Triangle' era of Superman books, but I always felt like Lois would have a really angry day with Clark going through all the times she saw him and Superman together and making him explain how she was fooled. "...robot...robot...Batman...split into two people by magic...time-travel...robot..."