Anybody else know you should have a different surname?

Question:

Anybody else know you should have a different surname?

My great-grandfather and his first wife parted company, and while she was still alive he took another 'wife', my great-grandmother. The children should have had her name and not his. Any others with another surname, now sanctioned by time, and how did it happen?

By coincidence they're both famous Civil War surnames, so if I added the other surname it would make me look like some Civil War buff.

Best Answer - Chosen by Asker: So you're a fourth generation bastard (since it was illegal for your Great Grandfather to marry your Great Grandmother with his first wife still alive). Or as they say in Japan, "You come from a long line of batchelors". So what's new?