Did any medieval literature or mythology have vampires vs werewolves or is that just something modern authors and moviemakers have made up? Were there cultures that believed in both?
It is a modern, literary and cinemagraphic convention.
Northern Europe had traditions involving both werewolves and the walking dead. Vampires are a specific variety (drawing on a Balkan tradition), which thrive in literature more than the generic, trouble-making walking dead of Northern Europe. Little actually distinguished the Balkan walking dead from those of Northern Europe, but literature has emphasized the role of drinking blood - a bit more than one might find in the actual folklore. The real concern was the idea of corpses escaping the grave and walking around - which is never a good thing.
The idea that people could change into the form of animals is less at home the more one goes east in Europe. It is not common in Balkans - especially when one considers how popular the stories were in western and Northern Europe.
Later 20th C before you have these match-ups. I can't find them in 19th C horror stories. (Supernatural Horror in Literature, a wiki check, and reading too much period specfi.)
The question is, were there cultures that believed in both before the writers of the 1800's popularized them? Also, there's the problem that a good many pieces of fiction were later treated as factual reports, but I don't know anyone who has tracked this. I've just noticed stories presented as true that later I found the original version labelled fiction.