AHEAD OF IT'S TIME

Not even a sequel. I do like The Doctor Blew It as a tagline though.

There's actually an interesting story here (not involving double-domed antics):

Before starring in 'The Thing with Two Heads' Roosevelt "Rosey" Grier was a professional football player for the Los Angeles Rams. After his football career ended he was a bodyguard for Senator Robert F. Kennedy during his 1968 presidential run. He was guarding the senator's wife Ethel when the senator was assassinated. Grier grabbed the gun and broke Sirhan Sirhan's arm.

Bobby riding with his boys in '68. Rosey Grier is second from the right.

Also, note the ratings on those posters. One says "GP", the other says "PG". This is because The Incredible 2 Headed Transplant was released in 1971, before the Motion Picture Association of America (MPAA) had decided to address the "General Audience" notion of GP. The Thing With Two Heads was released in 1972, after the MPAA had replaced the GP rating with PG in an attempt to clarify a film's content: Parental Guidance Suggested—Some material may not be suitable for pre-teenagers.

But then, in 1984, moms everywhere threw down their neon fanny-packs containing their kids' halftime oranges and teamed up with batshit wielders of the cross to go ham on Steven Spielberg, who had released two questionably PG films that year: Indiana Jones and the Temple of Doom, and Gremlins. I think the PG panthers were just ready to pounce on Steven after he slipped this shit into Raiders Of The Lost Ark:

But then, Steven calmly suggested that the MPAA adopt a PG-13 rating, and everyone was happy... except 12-year-olds, who refused to eat their mothers' halftime oranges in protest.