Why is baptism usually received only once in Roman Catholicism?

In Roman Catholicism, baptism is received only once because it is understood as the sacrament of rebirth, through which a person is made new and permanently sealed with a spiritual mark of belonging to Christ.1

This sacrament signifies a total annulment of past sins and the emergence of a new person, incorporating the individual into the body of Christ. Because the baptized person is considered to be permanently transformed and initiated into the church, the rite cannot be repeated. Similar to confirmation and ordination, baptism is said to convey a special, indelible character on the soul of the recipient.12