Tennesseans in the Civil War, in the Federal Section, list two individuals:
Brandan, Gustavus, F. & S., 9th Cavalry, &
Brandau, Gustavers R., Surgeon, 11th Cavalry
It is my understanding that these lists were taken from the National Archives Compiled Services Records. As such, these are the spellings that should be used in contacting the National Archives.
There is, however, the possibility in transcriptional errors in reproducing one list from another.
George Martin