That is correct, you need both. 08L70-MJR-670 is the bracket that gets attached to the passenger grab rail and functions as extenders to move the attachment point outside the rear fender; 08L75-MJR-670 is the stay (steel tube loop) that the saddlebags bolt on to and then, in turn, bolt to 08L70-MJR-670.
Awesome, thanks for that. After reading the installation instructions it's obvious.
The pictures hosted as examples don't display the correct part, thus causing my confusion.