I especially remember how i was suprised when i heard the so called enclave theme for the second time in a different game when i entered the oil rig for the first time..
here take a look..
https://www.youtube.com/watch?v=u1l4EKcHSp8
and this is a shocker form 15 minutes ago:
https://www.youtube.com/watch?v=jD393Toe0M0
gues Mark Morgan was a busnessman more than a composer
no shame tho Guy's got to make a livin'
EDIT:
BTW: if you're looking into the tune itself it's been used in multiple places and mark morgan soundtrack is called diffrently as from FO1 it's been used in Followers map..
here take a look:
http://fallout.wikia.com/wiki/Followers'_Credo
si i belive this is what You're looking for as always download & convert to mp3
https://www.youtube.com/watch?t=29&v=OoRavV5pIrs