Question: Was it intentional that Joe Namath and Ann Margaret's names were each repeated twice on the screen as Sharon Tate walked into the theatre? (01:08:00)
Question: Why would Cliff and Ronnie just let themselves die killing zombies when they could've driven off to seek refuge?
Answer: It was in the script that they would die. Ronnie stated he knew it would end badly because the director gave him the full script ahead of time.
Answer: Yes, though the intention was not Tarantino's. What is onscreen is the trailer of the (real) 1970 film "C.C. and Company", which starred (as you might have guessed) Joe Namath and Ann-Margret. Said trailer showed their names twice, a stylistic choice that emphasized the film's stars, and Tarantino used the unaltered trailer in the film.