We have to be careful about viewing innocent phrases through the prism of modern language. There’s the famous Joker story where he talks about “boners.” In the 40s, a boner was just a gaffe, a mistake, but in modern slang it’s meaning is quite different. There was no innuendo by the writer. I dunno what year that cover is but I’m fairly sure using “sandwich” as sexual slang is a pretty new phenomenon.
Now the bondage scenes and the infamous “headlights” covers, those guys knew exactly what they were doing