My grandma's actual birthday and official birthday were different - her father, not an English speaker, had, so goes the family legend, misunderstood the form he was filling in and put down the date he was filling the form rather than the actual date of birth which was three or four days earlier.
If my grandma could have been bothered she could, I suppose, have had her official birth date changed to her real one. If, that is, any documentary evidence of the real date in 1905 had ever come to light!
She wasn't a PPRuNe reader though.