Most likely cardioid, just cheap microphones supplied with a cheap deck. In any case it is a simple experiment that anyone could do. It made be a believer for headphone listening at least. Sadly I don't think that I have any actual binaural recordings. In my limited experience binaural recordings do nothing special over speakers.
I did a search of "binaural" in my Discogs collection and Alan Parsons Project "Tales of Mystery and Imagination" Blu-ray popped up. What a coincidence as I just listened to it yesterday in surround via speakers of course.
This quote from the release notes. "("Arrival" and "Pavane" recorded at Abbey Road in August and November 1975. Thunder and storm effects on "Arrival" recorded outside Abbey Road Studio Two during a freak storm, using a binaural "Dummy" recording head.)"