Coppola violated my own personal rule, which I call the Elephant Man rule. If a piece of music has been used so effectively in another movie that it's associated with that film, or has become iconic, then you should find something to else to use in your film. I thought David Lynch used Barber's Adagio for Strings so perfectly in The Elephant Man that Oliver Stone should not have used it in Platoon (it's now one of the most overused pieces in history, which is sad, because it's so good). Clearly I'm the only one who thinks this, as everyone associates the Adagio with Platoon, and it hasn't stopped Coppola and everyone else from recycling stuff.
Both Stone and Lynch got their cue from the death of Princess Grace when the Barber Adagio was used at her funeral in 1982. This was the first world-wide, celebrity-type function that I know of in which this so piercingly emotional score was used.
I think it's a fairly common thing to use music of a deceased composer and which music may no longer be covered by copyright. I suspect that is so with Samuel Barber (who only died in 1981) and of course with Puccini (of whom Chase also seems to have a certain fondness).
How many times have any number of (classical) composers' music (Chopin, Rachmaninoff, Bach, Puccini, et al) been used in many different movies – and TV shows? How many noticed the seemingly misplaced beautiful arias from "Madame Butterfly”" (Puccini again) in that searing sex-drama, "Fatal Attraction."?
But more importantly, the Adagio for Strings was not
written specifically for "Platoon" or "Elephant Man", nor the Cavalllerai Rusticana excerpt (Intermezzo) written for Raging Bull or GF III.
Now this would a 'bull' of another color if these directors-producers used the scores or themes of living composers without permission, especially those themes written specifically for certain movies, such as the many, many beautiful, movie themes of Ennio Morricone.