My (deceased) grandmother's birth name appears in the Registers as [Lebègue, Sabas Marie Eva] and her sister's name [Lebègue, Marie Daule Georges]. They both were born in Martinique around 1885. We used to call them Eva and Georgette, respectively. Now, I have three questions: (1) aren’t Sabas and Georges boy's names? or in the old days it didn't matter to use those names indistinctly?, (2) isn't Daule a Family name? , why is it inserted in the middle of the name , and (3) am I missing something about the structure of old French names?
Sabas can be a girl's name as well as a boy's name (what is called in French a prénom épicène): see here.
There is an old tradition which is to give the first names of the child's godfather and godmother as second or third name (the order does not matter). A child can then have a second or third name that belongs to the opposite gender. What is common, though, is then to give the matching name in its feminine or masculine variant (ex: a girl with a godfather named Georges could have "Georgette" as 2nd name).
Another christian tradition consists in giving a second or third name that invokes a saint, which is supposed to put the baby under his/her protection. In some families, it is common for instance to give "Marie" as second name even to boys.