score:8
I suspect it should read a 'duad of sons', not a 'daud of sons'. A duad is something made two parts. Compare it with triad or monad.
The Nestorian position is sometimes described as teaching that Christ is a duad, composed of a divine person and a human person. According to this, Jesus was not a single person who was fully man and fully God. Instead, the human son of Mary and the Divine Son of God, the Word, were closely connected but not united. (The nature of this connection differs depending on the version of Nestorianism.) In particular, Nestorius argued that Mary was the mother of the man Christ, but was not the mother of the Word. As such, he was accused of dividing Jesus into two persons, two sons.
The Chalcedonian position is that Christ is a single person with two natures. This unity is such that it is not possible to separate the actions and experiences of Jesus into human parts or divine parts. In opposition to Nestorius, they taught that Mary is the Theotokos, mother to the Theanthropos Jesus, both human and divine.