Having been a former employee of AAP, you'd be surprised of the amount of knuckleheads that only replace one rotor. Granted there are certain circumstances, but it has been done more than a few times.
As for the state question, just the way the distro center works. Its actually a pretty efficent system. There are screw ups with everything, and I've seen it happen more than a few times when things were ordered and didn't show up when they were suppose to. And yes, it is very irritating to get one and not the other. In a perfect world, they are to call you and tell you that your order is in, etc....
Tap the rotor with a hammer to see if it'll come off that way. WD-40 or PB bead plaster should help with the rust if it is indeed rusted on. Let it soak over night and then back to the hammer. If all else fails, BFH fixes everything.
