Saint Paul's doctrine, "One Lord, one faith, one Baptism" (Ephesians 4) was reaffirmed by the Council of Trent, explicitly defining that Baptism imprints a spiritual and indelible character.
The nature and efficacy of this character forbid the repetition of the Sacrament once validly administered.
This traditional teaching is emphasized in the New Code of Canon Law.
When reasonable doubt exists concerning the fact or validity of Baptism the Sacrament is administered conditionally.
This cannot be called a "rebaptizing" in the sense of a repetition of the Sacrament.
The controversy on rebaptism between Pope Saint Stephen and Saint Cyprian of Carthage is celebrated.
New Catholic Dictionary