Margot and
Margaux sound the same.
Margaux Hemingway's name is a nod to Chateau
Margaux, where a well known French red wine is made. So, yes, the French use
Margaux, but not for humans!
Here in South
Africa, French is becoming more widely taught and known, but we sometimes startle people with a real knowledge of it ... for instance, the problem that
Charles is spelt the same in French and English is often "solved" by local parents by naming their sons Charl. And there was a beauty queen some years ago whose name was Cezanne - nothing to do with Impressionism, I fear, just a new take on
Suzanne.