Surname Change on Records

[JOHN08]

I have a number of records referencing the same person; however, the surname is different. For example, I have Annanicola Saviotti, Annanicola Graziani, and Annanicola Placentini, who are the same person, married to Luigi Mizi.

The following is a short chronology of this family:

Abt 1786, birth: Mariantonia Mizi, father: Luigi Mizi, mother: Annanicola Saviotti.

Abt 1790, birth: Bernardo Mizi, father: Luigi Mizi, mother: Annanicola Saviotti.

Abt 1791, birth: Francesco Mizi, father: Luigi Mizi, mother: Annanicola Saviotti.

Abt 1792, birth: Antonietta Mizi, father: Luigi Mizi, mother: Annanicola Graziani.

Abt 1794, birth: Maria Concetta Mizi, father: Luigi Mizi, mother: Annanicola Saviotti.

10 Dec 1801, death record: Luigi Mizi, husband of Annicola Placentini.

9 Mar 1804, death record: Annanicola Placentini, wife of Luigi Mizi.

18 Feb 1816, marriage record for Mariantonia Mizi has the death of Annanicola Saviotti, her mother, on the 9th of March 1804. So, Annanicola Saviotti and Annanicola Placentini are the same person.

20 Sep 1817, processetti for Francesco Mizi (his birth record had
his mother: Annanicola Saviotti), father: Luigi Mizi, mother: Annanicola Placentini.

What could be the explanation for the surname changes?

Thanks for any help.

John

[Italysearcher]

You don't say which town this is but given the dates I assume that those birth records prior to 1809 at least are actually baptism records. A mother wasn't always present at the baby's baptism but the priest usually got the information correct. He got the mother's surname wrong on just one occasion. 3 out of 4 ain't bad.
Death records are not 100 % reliable as it depends on who is declaring the death.
Wives' surnames weren't considered that important. In many early parish records they don't even put the surname of the mother on the baptism record of her child.
In 1816 civil records are in force and much more attention is paid to accuracy. Hence you are back to the original baptism record for accuracy.
For the 1817 processi you are looking at a document (probably the father's death record) which gives the surname provided at time of father's death. Many 'processi' were parish records.
Hope this helps.