Plagiarism in Movie Musical Scoring

[K_h]

Does anybody know how common it is (for people doing the musical scoring to
a movie) to plagiarize musical scores from other movies or television shows?
For example, major parts of the background music in some movies is taken
from other movies and TV shows because it is identical -- or very nearly so.
These include:


1. Psycho 3 (1986) <---> Silver Streak (1976)

2. Alien (1979) <---> Fantastic Voyage (1966)

3. Independence Day (1996) <---> Poseidon Adventure (1972)

4. Star Wars (empire) <---> I Dream of Jeannie (1965)


Here, <---> means "background musical scoring is the same as". The
background musical score for key parts of "The Empire strikes back", and
others in the Star Wars series, plagiarizes the melody from the first season
of "I Dream of Jeannie" episodes 6 and 23: "The Yacht Murder Case" and
"Watch the Birdie" respectively. In episode 6, as Colonel Bellows parks his
car at Captain Nelson's house, and in episode 23, as a General watches
Captain Nelson hit a golf ball 400 yards, the menacing melodic tune is the
very same melodic tune used at various times in "The Empire Strikes Back"
and later star wars movie sequels. The musicians hired to produce musical
scoring should not plagiarize other people's work. These are just some of
the examples I have encountered; there are others but I've seen but can't
think of them off-hand. Does anybody know how common this is?


K