Not specifically relating to the Carden/Carden switch, but I know some
families in the Southern US were divided by the Civil War (or "War between
the States" for those who prefer that name.) Might this be one of the many
reasons a branch of the family would change their name? I think so. There
is also illiteracy, poor record keeping and just plain wanting to be
different to consider.
Accents may also play a part. I am told that my Preddy line was PRIDDY in
VA, but the spelling changed in one generation and reason given as "that's
how it is pronounced here and it is easier to change the spelling than the
dialect." My own (married) name looks like Rodrigues, but is pronounced
Roderick. We have always used the "real" spelling while my husband's
brother tired of explaining his name and changed to Rodrick. There are as
many reasons as people.
Back to CARDEN/CARDIN -- Orange Co., NC had many CARDEN in the early 1800s,
but my Patsey brick wall had CARDIN on her marriage bond. I'm still trying
to determine if this wife of Harrison Woods was CARDIN/CARDEN or ??? and who
her parents were.