Your trivia is wrong. I saw this double feature in 1979 and the movie called Grave Desires was a totally different movie. My memory is vague, but I seem to recall that the movie was European. That's all I can tell you. Thanks for letting me tell you this.
shareI checked Grave Desires title, and you might be right. The movie you may be thinking of is, Vampire Night's Orgy. Sinister Cinema has (had) a Drive in double Bill of Count Dracula's Great Love with Vampire Night's Orgy as the second feature.
Hmmm, Count Drac's Great Love (Cemetary Girls) and Vamp's Orgy (Grave Desires)
Yes, I have too much time on my hands.