Petra Von Kant , Vera Vague ??

Vera Vague refers to a character created by Barbara Jo Allen in the 40's. Petra Von Kant, I assume, is a reference to the title character in the Rainer Werner Fassbinder's film The Bitter Tears of Petra Von Kant from 1972. Why? I honestly don't remember, but they are both man devouring characters if that helps.