I would have to look at the census but what I think you saw was where it asks all males 21 years or older if there citizenship have be restored. That required all men in the south to swear allegency to the Union to get there citizenship restored. The requirment was so the state could return to the Union. Most did it from what I have seen. President Johnston called for the south to do this but the Radical Republicans still preventing former Confederate States from automatic being readmited. Naming a child the maiden name of there mother or grandmothers was common. It was very common among we Scot Irish. This was also done to males. Often several brothers having the same middle name.