i have the Johnny Carson limited video collection and it has his name on the front cover that i cant see in any other photo. i think it might be real and not printed because it has a different feel from the glossy cover and parts look smudged/worn off.
the reason i thought it could be real is they obviously made a few thousand of the set and mine is the only one that have ever seen with his signature on the front.
it's possible they could have made a limited number with it stamped on the front for like a fan club,promotion,pre-order, or someone paid to sent it in to him and his secretary stamped it.