As people get divorced, remarried, and have different sets of children, the mother's surname helps a great deal in establishing identity of a person.
In our tribe, it was a custom to reuse or recycle names of children who died in infancy
by mothers, and stepmother's and resukted in a lot of confusion.
It was also customary to name at least one grandchild after a grandparent of either sex. A grandson may be named after his grandmother, and he assumes the masculine version of the name. Teofilo for example may have been named after his grandmother Teofila,
Exequiel may have a recycled name from an older brother who died in infancy.
This results in a baffling birth certificate, and baptismal certificate.
That's another reason why we should be careful not to merge two profiles just because they have the same name and were born around the samet time - check to make sure that one or the other didn't die in infancy or childhood before the other was born. It would be a shame to sort of delete a person's soul by taking him or her out of the tree just because his or her life was short.
Forgive me for being a little poetic or spiritual here - I get like that around the High Holy Days!