Here is quote from St. Bede concerning the unity of the four Gospels...
But though there were four Evangelist,
yet what they wrote is not so much four Gospels, as one true harmony of four books. For as two verses having the same substance, but different words and different metre, yet contain one and the same matter, so the books of the Evangelists, though four in number, yet contain one Gospel, teaching one doctrine of the Catholic faith.
