Wouldn’t you just say one was born X AM/PM (daylight savings) and th either Y AM/PM (std time) ?

My granddaughter was born on my friend’s birthday. But in Australia, which led me to telling my friend that my granddaughter was born on his birthday which is weird because his birthday wasn’t until tomorrow.

Or being born when countries switch time zones.

There was one Pacific island that went from 30 Dec to 1St Jan because they were switching from + GMT to -Gmt.

I know twins who have different birthdays. I don’t think they’ve met a sphinx though.