u/SeweRSlug26

Civil War ancestor fought in both sides?

my 4th great grandfather Berry Benjamin Turner and his brother James R. Turner fought for the union in the 12th Tennessee Cavalry. They would have been between 17 and 18 years old with Berry being the elder brother. In Berrys discharge record i have in my home it says he enlisted January 13 1864 in Nashville James digital pensions say the same. However i’ve recently come across a prisoner of war record showing both Berry and James having been part of the 39th Georgia Infantry and released in Nashville January 6 1864 under order of MajGen. Grant. Why might it be that they served on both sides? Could they have defected to the union together?