I don't know about the use of
Maria in Iberia/Italy, but it may interest you to know that in Irish/Gaeilge there is a version of
Mary used only for the BVM. She is Muire, which is never used as a given name.
I would be interested in knowing if this was ever reflected in the use of the vernacular/written Latin used in the Irish church? As far as I know it isn't and
Maria was used for
Mary, for both the BVM and the given name
Mary in Masses, and church registers, etc.