N.C. Gen. Stat. § 15-6.2: Concurrent sentences for offenses of different grades or to be served in different places.

When by a judgment of a court or by operation of law a prison sentence runs concurrently with any other sentence a prisoner shall not be required to serve any additional time in prison solely because the concurrent sentences are for different grades of offenses or that it is required that they be served in different places of confinement. (1955, c. 57.)