When more than one stands alone, it usually takes a singular verb, but it may take a plural verb if the notion of multiplicity predominates:
The operating rooms are all in good order. More than one is (or are) equipped with the latest imaging technology.
When more than one is followed by of and a plural noun, the verb is plural: More than one of the paintings were stolen.
What does multiplicity exactly mean here?
Secondly, I cannot check on Ngrams, but feel the singular is right in the second example