Chapter 16 — Part II: The Sacraments — Baptism
Section 118. In Conditional Baptism The Sacrament Is Not Repeated — Nor let anyone suppose that it is repeated by the Church when she baptises anyone whose previous Baptism was doubtful, making use of this formula: If thou art baptised, I baptise thee not again but if thou art not yet baptised, I baptise thee in the name of the Father, and of the Son, and of the Holy Ghost. In such cases Baptism is not to be considered as impiously repeated, but as holily, yet conditionally, administered.