Passages in the Gospels where there are seemingly identical accounts of an incident in Jesus's ministry are the more interesting where there are also significant differences involved. Here in this account in Luke of a miraculous haul of fish it all seems very straightforward, but there is also such an account in the Fourth Gospel with strong similarities and some marked differences.
The account in the Fourth Gospel takes place right at the very end, after the Resurrection; in Luke, however, it is at the beginning of the Galilean ministry, at the point where Jesus begins to acquire followers. Incidentally in other Gospels the acquiring of disciples is startling different: in Matthew and Mark we are also by the lake, but the scene is very different; in John, by contrast, it begins where John is baptising -- it would seem that Jesus takes over some of the Baptist's disciples.
But back to the 'miraculous' haul. Are these two quite different incidents, or are they in fact much more closely related? First of all we have to get rid of any idea of the Gospels being accounts of what Jesus said and did -- although they seem for the most part to be presented in this way. They are not accounts, but rather presentations, interpretations. They are based on a mixture of experience, memory and story telling.
The early disciples, after his death and resurrection, came to realise that Jesus fulfilled in his person, in his teaching and through what happened to him, all the hope and expectation of the traditions of Israel. They understood him as the Messiah, Saviour/healer and Lord of Justice. They began to interpret all of what had happened within this context: what had been passed on of his words and teaching, in the stories which had come down to them. (Matthew and John may possibly have had first hand experience of him -- but even then one's memory can weave wonderful webs of appreciation and understanding; no one has claimed that Mark or Luke had such knowledge.) Thus were the Gospels written up to present Jesus as the Christ.
Even though there are strong similarities between Mathew, Mark and Luke, whose Gospels seem at first sight a simple account 'of what actually happened' nevertheless each one is as it were grinding his own flour from the wheat of tradition -- sometimes in remarkably different ways, with very different overall results. By contrast the Fourth Gospel seems to come from a very different stable. Its whole style is different; the way it presents Jesus -- with those magnificently engineered -- punctuated by sharp and poignant statements (did Jesus really say 'Before Abraham was I AM' or 'Thou sayest it' to Pilate?)
For a long time, before criticism was even possible or seen to be an essential way towards the understanding of the Bible, it was naively thought that whereas the Synoptic Gospels told the story of what happened, The Fourth Gospel was a poetic and theological construction presenting an idealised Jesus -- consider the opening of the Prologue.
It is now realised, however, that John, even with its fantastic flights of inspiration, is sometimes (often?) closer to the primitive tradition/experience than are the other Gospels. The account of the calling of the disciples is one example; the 21st chapter in which that other miraculous haul of fish is described is possibly another. For ages that last chapter of John was almost in effect dismissed as a more or less empty fantasy tacked on to the Gospel proper. Modern scholars have shown how it possibly goes right back to a very early strand of the tradition and is richer than was ever thought.
What does one make of that Eucharistic breakfast by the shore in which the primary elements are not bread and wine, but bread and fish -- put in the context of that miraculous haul -- or vice versa? 'It is the Lord' cries out the Beloved Disciple. Compare this with Peter's 'Depart from me, I am a sinful man!' Two very different messages set around the same incident -- or is it a different incident? It is interesting that both are associated with a special commissioning: in Luke Jesus says to Peter 'Do not be afraid (the standard assurance in the context of a theophany), from now on you will fish for men.' In John 'Feed my sheep!'
Thank God for the Gospels not being just simple accounts of what Jesus said and did; that they contain such puzzles and even contradictions is to their enrichment. The 'Good News' is all the more powerful and compelling -- and far from simple!