Great-grandpa (her husband) had fathered a child out of wedlock with his mistress at the time his wife also became pregnant, so he stole the deceased baby's identity and gave it to the illegitimate child and married the mistress, thinking he had covered his tracks. Nobody knew what he had done until I pieced it all together about 100 years later, discovering two different people who had the exact same name, birthdate, father and birth certificate. One died as a baby and the other lived to old age. Looking forward to asking my great-grandpa about that. 🙂