The RCIA #73 states: Ordinarily when catechumens are present in the assembly of the faithful during the Mass they should be kindly dismissed before the liturgy of the Eucharist begins. They must await their baptism, which will join them to God’s priestly people and empower them to participate in the celebration of the Eucharist. Therefore, catechumens should be part of the dismissal rite.
Baptized candidates from another Christian tradition are already members of the Church [though not in full communion] and children of God. Their baptism gives them the right to be present at the celebration of the Eucharist but they may not receive Holy Communion until they have been received into full communion with the Church. When these candidates are truly uncatechized they may choose to be dismissed with the catechumens, however, they must be continuously reminded of the fact that they are not catechumens.
Baptized Catholic candidates are never dismissed. By their baptism they have a responsibility to be with the community for the celebration of the Eucharist.