I've passed this topic along to a couple of friends who came up with other examples:

One woman's daughter was married, so both were, let's say "Jones". But the marriage was on it's last legs when the baby was due, so her daughter refused to put "Jones" on the bc, and instead put her own maiden name, which she used again after the divorce a few months later.

Another couple had a locally infamous last name and just plain didn't want the kid saddled with unfair assumptions...Oh, he's a JONES??

(No offense to any Joneses out there!!)