On 1965's "The Cincinnati Kid"

And the sadistic bastard who decided to put Ann Margret (then 24) and Tuesday Weld (then 21) in multiple scenes together was who exactly (had to go to a damned X movie just to chill)?.............................................................................P.S. It's also kind of a ripoff of 1961's "The Hustler", the only difference being the game (poker versus billiards).