Trying to make sense of the word "vulgo" - adoption, or alternative name?

[pepecintra]

Hi Guys
I came upon the marriage records for my 2GGM, and I don't know what how to interpret the text.
Her name was Fiminola Gherardi, this is the name she used everywhere (birth records for her children, immigration records, death record). She was married to Francesco Marinai, and was the daughter of Vincenzo Gherardi and Faustina Gentilini.
She was born (1853) and married (1872) in Pontedera, Pisa. The birth records are not available online, and neither are the Allegati. The earliest I can go is the Marriage Atto/Pubblicazione. She died in Brazil.

The question is: on her marriage records (both Atto and Pubblicazione) it is stated that she had another name. I see these variations:
- "Vittoria vulgo Fiminola Gherardi" (from the Atto)
- "Vittoria Gemma vulgo Fiminola Gherardi" (from the Pubblicazione)

I know that "vulgo" means "a.k.a"., and that it would be used when someone is registered with a name but is later identified with another one (specially when there's someone else with the same name around). Therefore, I would believe that her Birth Record would say "Vittoria" instead of "Fiminola". But my question is, that is the "Gemma"? Is it a middle name, or a surname? If it's a surname, can it be a sign that she was adopted? I mean, maybe she was originally registered as Vittoria Gemma in the orphanage, and then became Fiminola Gherardi when adopted? If adopted, would this be an information that they would have included in the marriage records like this? Or I am going over my head, and Vittoria Gemma is just a double worded given name?

(I haven't yet found another Vittoria Gemma Gherardi that would justify she having an alias)

These are the original records:
Atto n.81: https://www.familysearch.org/ark:/61903 ... 644?i=2032
Pubblicazione n.84: https://www.familysearch.org/ark:/61903 ... cc=2043812

[mmogno]

The bride is Vittoria Gemma, commonly known as Finimola, Ghelardi. The surname was rectified on 29 August 1891 by the Court of Pisa from Gherardi to Ghelardi, as shown in the side note of the marriage certificate.