I believe that I have across a similar situation regarding a child having
the same name as her mother, in my own family
According to the census records in the village where my father was born
in present day Poland, my father's mother name was Chaja-Raca. According
to the same records, her mother's name was Rachel (nee Portek) and her
father was Moise Parenczev.
However, my father and his two brothers always referred to their mother as
Rachel, not as Chaja-Raca. Moreover, they believed (and wrote in an
application for a social security card) that her maiden name was Portek (the
maiden name of her mother).
In essence, then, my grandmother seemed to assume the TOTAL identity of her
own mother. However, on my grandmother's stone, in London, her name was
indeed given as Chaja Raca, daughter of Moise. so, someone in the
synagogue knew something more than the family did, apparently.
She and my father and his two brothers had already passed on when i
discovered this fact, so I had no opportunity to question anyone about it.
A partial explanation regarding the Portek/Parenczev switch was that her
parents marriage may not have been not "officially" registered, and the
offspring of such marriages were known to officials by their mother's
(maiden) name rather than their father's surname as is customary in the
west. Hence Chaja Raca was recorded in official records (the census and
emigration papers?) as Chaja Raca Portek.
As for her first name, I have heard two possible explanations:
1. her mother died in childbirth or early on and the child took over her
mother's name, for everyday usage, to honor her, although her "real"
Hebrew name did not change.
2. Rachel is one way to anglicize Chaja-Rasa, but of course on her stone her
name would be expressed accurately as she was given it at birth.
I'd be interested in any other thoughts others may have on this.