I don't know if it's been done - but does it matter? Write it!
What if we all said, 'eh, someone already wrote a story with a revelation' or 'someone already wrote a variation on TOGOM'? Wouldn't the fic world be poorer if we all stopped writing because someone had a similar idea?
Write it anyway!
Sue (who would like to read the story you were going to write where Lois had to check and make sure Clark was really Superman)
Lois: You know, I have a funny feeling that you didn't tell me your biggest secret.
Clark: Well, just to put your little mind at ease, Lois, you're right.
Ides of Metropolis
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