Thanks for answering, but I'm afraid you're mistaken. Tested it in the simulator today. Only the RHS has MASTER-indication, but the LHS is NOT slaved. Read my first note from the FCOM:
Note: In VOR LOC or APP mode, the A A/P and Captain’s F/D use selected
course and navigation data from the No. 1 VHF NAV receiver.
So RHS show correct tracking, LHS shows an offset F/D. When A/P IS engaged I understand it's value, because you'd want to know what F/D-bars the A/P is following. On the other hand I'm not sure I get it if we were to have the same setup and the A/P's off.