I've never seen anything like that hoDS poster either. I wonder whether it was part of a standee that would have been a lobby display; the other part, which presumably he discarded, would have had the title, slogans, etc. on it.
The monochrome Barnabas poster looks like something that would have been produced by the Philly Gum co. (whatever their actual name was) that produced the gum cards. That's the picture that you could make by piecing the cards together on your bedroom floor (I did that many a rainy afternoon...). I think the same poster used to be sold in the back of Famous Monsters of Filmland magazine.
cheers, G.