Diacope (pronounced die-ACK-oh-pee) is where a word or phrase is repeated after a brief interruption.
One of the best known examples, voted the 22nd greatest line in cinema, is “Bond, James Bond.”
“Fly, my pretties, fly” is another well-known example from another film, The Wizard of Oz (although it doesn’t actually appear in the film–diacope has exerted its power by changing what is remembered).
Other examples from politicians, which again were never actually said, are Harold McMillan’s “Events, dear boy, events” and James Callaghan’s “Crisis, what crisis?” I suppose that Theresa May’s “Brexit means Brexit” is another, much poorer, example.
Vocative diacope is where you simply insert a name or title between the repeated words: “Zed’s dead, baby, Zed’s dead.”
It can be more than one word: “Do you remember an inn, Miranda, do you remember an inn?”
The other form is elaboration where you add an adjective: “From sea to shining sea.” “Sunday bloody Sunday.”
The extended diacope has the form AABA rather than simply ABA: “A horse! A horse! My kingdom for a horse!”
“Romeo, Romeo, wherefore art thou Romeo?”
“Alone, alone, all all alone”
“Free at last. Free at last. Thank God almighty we are free at last.” Martin Luther’s epitaph
“To be or not to be.”
All of this is taken from Mark Forsyth’s useful and very readable book “The Elements of Eloquence: How to Turn the Perfect English Phrase” https://richardswsmith.wordpress.com/2017/12/22/the-figures-of-rhetoric-i-alliteration-full-five-fathom-deep-thy-father-lies/