score:1
This conundrum is resolved by the device of Conditional Baptism.
The Church of England states thusly:
Conditional Baptism
If it is not certain whether a person has already been baptized with water in the name of the Father, and of the Son, and of the Holy Spirit, then the usual service of baptism is used, but the form of words at the baptism shall be
N, if you have not already been baptized, I baptize you in the name of the Father, and of the Son, and of the Holy Spirit.