I'm a little surprised there wasn't an NBC C&P guy standing off-camera, with a line of sight on the desks, specifically to catch this sort of sleight-of-hand in the act, on the off-chance anybody got any funny ideas.
You wouldn't need a
cut and paste guy in LOS, Mark Goodson Productions had a sterling reputation at that point where they could run their own ship and you'd go to the lawyer were there an issue.
It does go to how the format of "match and you're done" that someone might figure out that if they don't match they will get more time in the spotlight, but celebrity panelist is a symbiotic job--the host talks to the stars and builds them up and allows plugs, and the star players make the show look good. If Fred is getting a thousand dollars twice a week to show up, play the game and be a good soldier why but shoes in the gears? Frankly he comedians are there to be funny and Fred was a bright spot in an unfun atmosphere.
Imagine how discreet that someone would have to be to get away with that over and over again. Write two answers, grab the "proper" answer for the situation, lose the unused card and do that four times throughout the opening half. It would be better to write tangential answers that are unlikely to score than to just write "Flugelhorn" over and over.