A possible contradiction has been identified, in that in Mark Jesus exorcises a demoniac in the region near Gerasa; (Mk 5:1) in Matthew it occurs in Gadara. (Mt 8:28) However, the former is probably a city; the latter, a province (so Blomberg, DJG).  If so, it’s rather like one person saying that something happened ‘near Norwich’, and another saying that it happened ‘in Norfolk’.

‘The problem of the city’s name is a classical one and goes back at least to Origen’s time. The city of Gerasa lies approximately thirty miles southeast of the Sea of Galilee, and as one commentator somewhat sarcastically states, “The stampede of the pigs from Gerasa to the Lake would have made them the most energetic herd in history!” (Fitzmyer).’ (Stein, NAC on Luke)