In 1954, DuMont came out with a "Duoscopic" TV set that allowed two people to watch different programs on the same set, simultaneously. From Newsweek (Jan 11, 1954):
"When a husband wants to look at the fights and his wife prefers a situation comedy, the Duoscopic provides both at the same time. The set contains two screens and a special mirror that throws one picture onto the other, creating a double image. Polaroid windows filter out the unwanted image, and special earphones carry the separate sound tracks."
It was priced at $600. So in 2015 money, that would be approximately $5304 (according to the US Inflation Calculator). At that price tag, it made more sense for couples with different viewing preferences to just buy 2 TV sets and sit in separate rooms.
There's more info about the Duoscopic TV at the Early Television Museum. On that site, there's also speculation that DuMont originally developed the Duoscopic TV as a 3D TV, but decided they couldn't get that to work fully, so they repackaged it as a "watch 2 channels simultaneously" TV.