If you ever want to laugh at genealogists, look up French surnames. They changed if the family moved, were given differently depending on which area of the country your family was in, were often based on physical appearance and belonged to only one person so you might have Guillaume, son of Robert le Gros (the large or the fat), who had a big nose, so he was Guillaume le Nez (the nose), Fils de Robert le Gros (William Lanay FitzRobert or William FitzRobert Lanay if he wandered over to England from Normandy) and he had at least one middle name, possibly carried his mother's name, and he had a saint's name as well (so that the saint would be watching over him). So in records he might be any of that, unless, of course, he was a traveling knight, a younger son seeking his fortune, someone who had been cast out of the family or was on the run or who simply didn't want their family identifiable for some reason, in which case he might be any of that, or William any of that LaRue or DuChemin. So in a will or legal document you might have William Olivier Paul Dumont Lanay FitzRobert LaRue deMaisonBleu (William Oliver Paul, the nose, of the mountain, son of Robert, on the road, who lives in the Blue House. But he was probably called Jean. (well, probably not exactly Jean, but something that had NOTHING AT ALL TO DO WITH HIS NAME)

My grandmother has SEVEN NAMES, three of which are last names (mother's maiden, own maiden, married). All of her relatives had the same issue. Her aunt? was called Caddie, which was not any part of her many many names but was the only one anyone used for her casually so the stories didn't match with the documents in, ya know, any way at all.