Yes, we need one of each to benefit from the full quality of books, but if we don't have a high volume of copying/scribing/illuminating, do we need 2 scribes and 2 illuminators?
As for high-Com, Good Teachers, we have my companion Christophoros the Schoolmaster (Com +2 and Good Teacher), Kareruren's Omphalos of Bonisagus (Com +1 and Good Teacher), Vespertilio's Liberius of Bonisagus (Com +4 and Good Teacher) and to a lesser degree Monkoflords' Agapitus (Com +3).