Properly speaking, this liturgical rite is called “Reception of Baptized Christians into the Full Communion of the Catholic Church.”
“The baptized Christian is to receive both doctrinal and spiritual preparation beforehand, adapted to individual pastoral requirements, for the reception into the full communion of the Catholic Church . . . Anything that would equate candidates for reception with those who are catechumens is to be absolutely avoided” (Reception of Baptized Christians into the Full Communion of the Catholic Church, #477.)
The reception normally takes place during Mass, with the high-point being the reception of the Eucharist. One makes a simple profession of faith and is received by the celebrant. Usually Confirmation follows.
Baptism cannot be repeated and can only be done conditionally if there is reasonable doubt that the baptism already conferred is invalid.
It is appropriate, according to the conscience of the person being received in the Church, to make a confession beforehand.
It is permissable to combine the rites appropriate to catechumens with the rites of the already baptized, but “care must be taken to maintain the distinction between the catechumens and the baptized candidates” (Christian Initiation of Adults, #506).
