Did Jesus free one man from demons in the country of the Gadarenes, or two?

Neither Mark nor Luke says that there was only one man, and naming one person who was present does not deny that another was there. Mark and Luke follow the man who stood out: the fiercer of the two, perhaps, as Barnes suggests, or the better known, whose case, Augustine thought, had grieved the whole district. He is the one who speaks for the demons and gives the name ‘Legion’, the one later seen sitting “clothed, and in his right mind” (Mark 5:15), and the one who begged to go with Jesus and was sent home instead, to tell what the Lord had done for him (Mark 5:18–20; Luke 8:38–39). Because his story went on, as he preached through the Decapolis, it was natural for Mark and Luke to centre their accounts on him.

Matthew, whose account is the shortest of the three, mentions both men, as he does with the two blind men at Jericho (Matthew 20:30), where Mark names only Bartimaeus. This is how independent witnesses commonly speak. As Barnes says, if Mark and Luke had plainly denied that there was more than one, while Matthew said two, there would be a real contradiction; they do not.

The Gospels and their manuscripts name the district in different ways (the country of the Gadarenes, Gerasenes or Gergesenes). Which town the name refers to, and where on the eastern shore of the lake the event took place, is a separate question.