Wikipedia
Conditional baptism
Mainline Christian theology (including Roman Catholic, Eastern Orthodox, Oriental Orthodox, Church of the East, Anglican, Lutheran and most other Protestants) has traditionally held that only one baptism is valid to confer the benefits of this sacrament. In particular, the Council of Trent defined a dogma that it is forbidden to baptize a person who is already baptized, because the first baptism would make an indelible mark on the soul. Therefore, in cases where the validity of a baptism is in doubt, a "conditional" baptism may be performed.
Usage examples of "conditional baptism".
She who could not yet use words nor understand them, had done what she had as if by direct instruction, in response to his attempt at conditional baptism.