Padrinos With Same Surname

Has anyone ever seen an example of a padrino for a marriage or baptism
that wore the same surname of either the parents or the couple being
married that WASN'T a relative?

Example. A person wears the name of Garcia and he marries someone and in
the record it lists that the padrinos were Juan Garcia and Manuela Lopez.

Has anyone ever seen an example in the records from 1800's (not modern
times) where that padrino surnamed "Garcia" was proven to NOT BE a relative?

NOTE: I know that the padrinos were not always relatives but I'm
wondering if there are examples of padrinos with the same surname of one
of the people involved have been proven to NOT BE relatives.

joseph

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Joseph Puentes
http://H2Opodcast.com (Environment Podcast)
http://H2Opodcast.blogspot.com/ (Blog for above)
http://NuestraFamiliaUnida.com (Latin American History Podcast)