This is a predicament. It's easy for me to say "Yes, ask each female if they need a pap" but I realize that's not always practical. However, if you don't you have a billing issue.
I used to go to my PCP for my annual physical and my GYN for my annual pap/physical. I believe they were both paid, so I'm thinking you are right, if they are done by separate drs, they are allowed. But I think most insurances do not allow them separately if done by the same dr.