Hmm, for some reason, now I'm reminded of an ero-game called Mama Love were the two main female characters are Moka and Kokoa look-a-likes. And now that it's been revealed that Moka's mom looks just like her outer self, suddenly that game's premise becomes more plausible.
Spoiler for nsfw:
Warning the following is
NOT WORK SAFE!
Open at your own risk.
Spoiler for nsfw:
Last Warning.
If you get in trouble, don't come crying to me about it.