I had the good fortune, Saturday the 5th of July, to find a Belmont Double Gothic. Didn't know such a thing existed! The stories run back-to-back, and each cover art takes half the space of the cover.
The 1st story is Hounds of Hell by Virginia Coffman [ironically it was one of her other titles I was searching for, which is how I came across this Double Gothic]; the 2nd story is Carnaby Curse by Daoma Winston. Both copyrighted 1967.
The one you showed looks like an older Gothic. I've run across many double Gothics (I don't recall the publishers) but their covers look a little different.