I've seen this once or twice - one example was Australia's WWII Prime Minister,
John Curtin. He and his wife
Elsie had two children, also called
John and
Elsie (couldn't they have been
Jack and
Beth?! *shakes head*). Anyway, in contemporary documents the daughter is occasionally referred to as
Elsie Junior, before she married. So I guess it's not common but not unknown either.