Have you ever been spanked by two ladies at once? Sadly, I can't say I have, except in my imagination. It's certainly a daunting prospect. The scenario offers many possibilities, none of which bodes well for your soon-to-be-very-sorry rear end.
They might take turns, each giving the other the chance to rest up between rounds.....
Or worse, they might take it on themselves to share your butt at the same time, each assuming responsibility for a cheek. Maybe they'll make a contest out of it, to see which of them can make you yelp the loudest, or can spank the fastest, or make your ass redder, or - well, you get the idea...
Or even worse (oh yeah, it can get worse), they might decide to do all of the above, but with canes...