Herleve of Falaise-2 has similar dates, and I've seen an internet theory that she was the grandmother of the first Geoffrey de Mandeville.
But the dates are impossible. His parentage is unknown. There don't seem to be any records of any Mandevilles before the Conquest.
The other Herleve seems to be fictitious. It's not known who her "husband" Gerard married, and her "parents" aren't known to have had any daughters.
