DC Universe: Two Lost Cities of Atlantis?

[Northern Piper]

To paraphrase Lady Bracknell, "To lose one city of Atlantis, may be regarded as a misfortune; to lose two looks like carelessness."

I was browsing some of my old comics the other day, and remembered something that has always bugged me: did DC ever explain how they had two lost cities of Atlantis, one with mer-people and the other with leg-people?

One lost city of Atlantis was populated with mer-folks. All the inhabitants of that Atlantis had fish-like tails instead of legs.

Then there's Aqua-Man's Atlantis, of which he was king at one time, complete with Queen Mera and annoying side-kick, Aqua-Boy. Everyone there had legs.

And, these can't be explained by alternate continuities, since Supes appears in both Atlantises (Atlanti?). He has the occasional dalliance with a mermaid (and Superboy appeared in mer-Atlantis at least once, only to have his memory wiped at the end of the story so he wouldn't remember it later when he was grown up. Honestly, Superboy's memory was so many seives, given the number of things he had to forget, like his Legion memories. However, that's beside the point.)

Supes also knows about the leg-Atlantis, since Aqua-Man is one of his colleagues in the Justice League.

Was there ever a point when Supes actually asked Aqua-Man about how many lost cities of Atlantis there were, or the omniscient editors tried to make sense of it?