There's always the swapped at birth option, as in
Good Omens:
There's a trick they do with one pea and three cups which is very hard to follow, and something like it, for greater stakes than a handful of loose change, is about to take place.
The text will be slowed down to allow the sleight of hand to be followed.
Mrs. Deirdre Young is giving birth in Delivery Room Three. She is having a golden-haired male baby we will call Baby A.
The wife of the American Cultural Attaché, Mrs. Harriet Bowling, is giving birth in Delivery Room Four. She is having a golden-haired male baby we will call Baby B.
Sister Mary Loquacious has been a devout Satanist since birth. She went to Sabbat School as a child and won black stars for handwriting and liver. When she was told to join the Chattering Order she went obediently, having a natural talent in that direction and, in any case, knowing that she would be among friends. She would be quite bright, if she was ever put in a position to find out, but long ago found that being a scatterbrain, as she'd put it, gave you an easier journey through life. Currently she is being handed a golden-haired male baby we will call the Adversary, Destroyer of Kings, Angel of the Bottomless Pit, Great Beast that is called Dragon, Prince of This World, Father of Lies, Spawn of Satan, and Lord of Darkness.
Watch carefully. Round and round they go . . . .
The Wikipedia article on secret identities may be useful
https://en.wikipedia.org/wiki/Secret_identity
