From what I'm aware, sections of music from EPISODE I were re-used in EPISODES II and III, and some parts of EPISODE II music in EPISODE III in action sequences either because the finished effects sequences were not ready for Williams to compose music to or there were extended/new sequences created after the music score had already been completed that needed music (i.e. the Droid factory scene in EPISODE II using parts of the earlier Coruscant/Zam chase). Williams normally redorded STAR WARS music with the LSO at the beginning of the year the film was to be released (i.e. with EPISODE ONE, I believe it was January 1999).

I personally like some of the re-use of the music in the later Prequels-to me, it gives the film continuity