N.C. Gen. Stat. § 163-82.9
If an applicant indicates on an application form described in G.S. 163-82.3 a current registration to vote in any other county, municipality, or state, the county board of elections, upon registering the person to vote, shall send a notice to the appropriate officials in the other county, municipality, or state and shall ask them to cancel the person's voter registration there. If an applicant completes an application form described in G.S. 163-82.3 except that the applicant neglects to complete the portion of the form that authorizes cancellation of previous registration in another county, the State Board of Elections shall notify the county board of elections in the previous county of the new registration, and the board in the previous county shall cancel the registration. The State Board of Elections shall adopt rules to prevent disenfranchisement in the implementation of this section. Those rules shall include adequate notice to the person whose previous registration is to be cancelled.
N.C. Gen. Stat. § 163-82.9