This may be a bit wild, but the other explanations are not satisfying to me either; so, I regard this as a contribution--as least as to a form of alternate solution and alternate coding for [RR]
RR/RM = white hats
This is still my opinion. Admittedly, my confidence has been shaken in Rosenstein; but, an alternate explanation for [RR] would fit my stubborn point of view.
I would point out that Q has other instances of using the same initials for more than one player.
With respect to Mueller ... he hasn't hurt POTUS yet, just taken out some spies and people with excess baggage (i.e., both Flynn and Manafort). Can Mueller really be so incompetent?? Or ... is it a smokescreen for the real game?
Someone on Reddit connected that #FLY[RR]FLY# with the lyrics of an Eagles song tweeted by Rothchild.
Alternate solutions are welcome. I respect your view, especially the hope that our nation’s high servants be honest.
That said, I suspect Mueller and Rosenstein to be black hats myself. Either way, I believe we will know the truth soon. God Bless.