All I am going to say is that it wasn't "double dipping." 1 person rode in the FP lane with a FP ticket, the second person rode with a RS ticket. The RS was the FP for the second person, as it was redundant (when using FPs) for the second person to have a RS *and* a FP.
Just to clarify what I mean...for us, it is just DH and I and DD. DD is 2 (32.5"), so too short for every height requirement ride. If DH rode Space Mtn using his FP while DD and I waited (say we're shopping), and then DH came back and took DD so I could ride space, why would I need a RS if I am also required to have a FP (since DH had used a FP)? There's no need to have 2 of the same thing.
Though I suppose what this could end up doing is *actually* creating double dipping. If I'm required to have a FP+ for DH to ride in the FP lane and get a RS pass, why wouldn't I use the FP+ upon DH's return and then keep the RS pass for later, since there's no time limit on it? Or switch my FP+ once DH returns (assuming availability)? I actually see a lot more potential for "abuse" of this than there would be to just give the second person a RS pass w/o requiring the second person have a FP+.