Coincidence or Plagiarism?
The plot of "Love at First Bite" (1979) is exactly the same as the plot from "Guess What Happened to Count Dracula" (1970). In "Guess What Happened..", Dracula has moved to LA to escape the communists who have overrun Transylvannia (including his castle). He now dresses in modern 1970s swinger fashions and has several kooky assistants (instead of just one). He falls in love with Cynthia when she visits his restaurant. He bites her a couple of times without her knowledge, but other than that doesn't do anything evil and refuses to bite her a third time (thus turning her into a vampire) without first getting her permission. Meanwhile, her boyfriend begins to notice the changes in her and gets jealous, while a psychiatrist dismisses his fears that she is falling victim to a vampire. Finally, the old boyfriend confronts the vampire, but Cynthia has decided she prefers Dracula and volunteers to be bitten a third time and becomes a vampire.
Add a bit of Hollywood gloss and a car chase, replace an evil vampire rival with some stereotypical blacks for a tangential fight scene, and, voila, you've got Love at First Bite. And with the writer/director of "Guess What Happened..." dead (he was killed around 1971 or 1972) and the original film largely unknown, you don't have to worry about being sued. (Why not? It's an honoured tradition. Shakespeare would go a step further and copy lines word for word.) Of course it could just be a huge coincidence that the two films' plots are exactly the same given the limited number of plots around...
As for which movie is better: you laugh where you are supposed to when you watch "Love at First Bite", whereas despite its being a comedy, you laugh at "Guess What Happened..." for all the wrong reasons, but I personally find "Guess What Happened..." to be a far more entertaining film.