[78-L] 20th Century Fox "For Rehearsal Purposes Only" 78s

[Clifford Bolling]

Just acquired a small group of 12 inch 78 rpm records with 20th Century Fox labels noting 'for rehearsal purposes only'. 
 
The first one is from STARS AND STRIPES - 1954 and includes Debra Paget singing 'FATHER'S GOT 'EM' and the flip side an instrumental snippet of 'HAIL TO THE CHIEF'.  
 
The other two are from THERE'S NO BUSINESS LIKE SHOW BUSINESS - 1954, the first featuring a short version of MARIE and the flip side is a noisy instrumental called CALL ME UP SOME RAINY AFTERNOON.  The 2nd of these is one sided, featuring Marilyn Monroe singing AFTER YOU GET WHAT YOU WANT.  I looked on YouTube and there is a video clip from this movie showing her singing this song and dancing.  Seems to be the same tune she is lip-synching to in the video clip.
 
Question -   Are these what would be played during filming so the performers could sing and dance in time to the soundtrack?  That would be pretty cool to think that Marilyn Monroe and Debra Paget actually might have listened to these records while making the movies!
 
You can view and sample these records at:
 
http://pdx78s.cdbpdx.com/20CF/
 
Any info would be appreciated!  Thanks!  CDB