I know.. i was just joshing about the seance part, Vick..LOL
I know that others here have posted theater-specific Cinerama posters for the theater here in LA, so I think it could certainly be a first release poster that was shown in the Cinerama venue.
Not sure if this means anything, but on the poster, lower left, (that you took a snap of), where it says "Metro-Goldwyn-Mayer et Cinerama" in the cinerama logo style, certainly could suggest that this poster was for a first release screening, too.
Did you try and find anything out about the printer and when they were in operation? Looks like G. Cravenne in Paris.
It's great art, too. The montage lets you know exactly what the subject of the film is about.