Why, to amplify meaning, of course. Or because you’re writing about Tudor England. In Hilary Mantel’s Wolf Hall trilogy, for instance, “all the leading male characters apart from Henry VIII are named Thomas (it was the second-most-popular name in Tudor England). There is Thomas Cromwell, the ruthless hero. Thomas Wolsey, the Catholic cardinal. Thomas More, the Catholic zealot. Thomas Cranmer, the archbishop of Canterbury. And Thomas Boleyn, the depraved father of Anne Boleyn.” – The Atlantic