I'm not an ROTJ expert, but after checking the CRL for a moment, it doesn't says anything about strapping underneath the shoulder bridges. (And yes, for us ANH/ESB troopers, we use white strapping.)
03. Shoulder Straps:
These must be securely mounted in front and may free float in back. They may be affixed with rivets, Velcro, or adhesive.
No visible rivets are allowed.
Shoulder straps should not have a flat end at the ends of them, they should be ribbed 100%.
These must be glued in front.
These must be secured in in back.
Should straps must be made foam other of flexible material instead of rigid plastic.
ooh, red font!