Yes, of course I've seen those movies, they're considered classics of 1950s sci-fi, particularly When Worlds Collide.
Generally, I rarely buy a poster for a movie that I haven't seen, and when I do, I try to track down the film so that I can watch it. This isn't to say that I always like the movie that the poster advertises: in the case of 1950s sci-fi, there are a lot of terrible titles with fantastic art, so I'm quite willing to overlook any artistic deficiencies if the poster is visually appealing to me.