In such situations, I can see the culture adapting so that you have a "real birthday" and a "celebration birthday". Famously, Queen Elizabeth II was born on 21

In such situations, I can see the culture adapting so that you have a "real birthday" and a "celebration birthday". Famously, Queen Elizabeth II was born on 21 April 1926, but her official birthday was also celebrated on the second Saturday in June each year in the UK.