I believe prior to V2, concelebration, though in a different way, was done at ordinations of priests and bishops. The newly-ordained priests say the Offertory prayers and the whole Canon, including the words of consecration, aloud with the bishop, kneeling around him. The words of consecration especially must be said “slowly and rather loud” and “at the same moment with the pontiff”. They must say the words significative, that is with the intention of consecrating, and must be careful not to say them before, but exactly with, the bishop). They receive Holy Communion under one kind. The same rite is used at a bishop’s consecration, except that in this case the new bishop communicates with the consecrator under both kinds.
The
Ordo Romanus primus of the 7th/8th century speaks of concelebration on certain feasts:
- On festivals, that is to say on Easter day, Pentecost, St. Peter’s day, and Christmas day, the cardinal presbyters assemble, each one holding a corporal in his hand, and the archdeacon comes and offers each one of them three loaves. And when the pontiff approaches the altar, they surround it on the right and the left, and say the canon simultaneously with him, holding their loaves in their hands, and not placing them on the altar, so that the pontiff’s voice may be heard the more strongly, and they simultaneously consecrate the body and blood of the Lord, but the pontiff alone makes a cross over the altar.