How do you change the birthdate for your kid younger than 13?
I accidentaly put wrong birth date for my kid. Is there any way I can correct this?
If not, can I create a same Apple ID with different birth date?
You can't change the date of birth of a child : Update the birth date associated with your Apple ID - Apple Support
Be sure to enter your correct birthdate. After you change it to any age below 13, you can't edit it.
If not, can I create a same Apple ID with different birth date?
You can't create another account with the same primary email address,