Well, with respect to the discussion here, if it's actually two services, you most definitely can not omit an MBJ in one of them.
Yes, to my knowledge that's never been an option for 2 services or 2 sets of service entrance conductors, only for pre-2020 NEC PV supply side connections, depending on interpretation. And my question was about 2 services vs 2 sets of SECs, no so much the PV supply side options.
I guess the negative effect of omitting 1 of 2 MBJs on 2 services has a chance of being worse than on 2 sets of SECs. With 2 sets of SECs, you'd have to omit both MBJs to end up with no fault clearing path, as the two neutrals are obviously interconnected. With 2 services, you might get 2 neutrals that have no continuity between them on the utility side, and so if you omitted 1 MBJ and 1 GEC connection, you could end up with no fault clearing path.
Cheers, Wayne