I think we need the Greek term, if someone would so reply, for the assisting concelebrants, in order to define exactly what their role is. But, to follow-up on what Jonathon, Reply #3, posted; in Orthodoxy, the diocesan bishop, the "Icon of Christ," presides; the parish priest, the presiding priest, presides in place of the bishop. There is only one "liturgos," i.e. liturgist/celebrant. The other priests who are vested and celebrating, are assisting. The celebrant directs what parts of the service the assisting celebrants perform. Notice, they do not stand in front of the Holy Table, but stand to the sides of it.
The only part of the Liturgy that is said jointly, by all the priests, is the commemoration of their bishop, "Among the First, Remember O Lord..." Even though it is done in this country, probably due to it's evolving history, only one bishop should be properly commemorated in this petition, again, because there is only one "liturgos."