Jeff, this should not be a big problem, pre-covid a number of Cat Shows were held every weekend throughout North America with many of the exhibitors flying to the shows with their cats. Many exhibitors use carry-on bags with a zippered divider in the middle to separate the cats.
https://sturdiproducts.com/collectio...-divided-large .
Yes you may need to take both cats out at screening, the screeners have no idea of the requirements of your airline.........or do they care. BTW if you are not comfortable removing both of your cats in the hub-bub of security clearance area, you can ask to be cleared in an enclosed room.
My best advise as a person who has flown many times with cats, try to be as unnoticeable as possible, once on the plane stow your 'package' asap and do not draw attention to it. My experience over the years has been that over 90% of my seatmates had no idea that I was flying with a cat, and why should they.
BTW if this does not work for you PM me as I do have a friend with reasonable pet transportation service connections.
Bob