Having let some time pass for investigation, the apparent conclusion here is No, it's not credible.
A Washington Post article titled "7 papers, 4 government inquiries, 2 news investigations and 1 court ruling proving voter fraud is mostly a myth", which admittedly takes a very strong editorial opinion on the matter, links to exactly what it claims to. Of note are the four government investigations, since they include North Carolina (as asked about) and Kansas (as the state which was running the investigative database):
Kansas' secretary of state examined 84 million votes cast in 22 states to look for duplicate registrants. In the end 14 cases were referred for prosecution, representing 0.00000017 percent of the votes cast.
A 10-year 'death audit' in North Carolina turned up a grand total of 50 instances in which a vote may have been attributed to a deceased person, most likely due to errors made by precinct workers.
Additionally, this article describes an investigation where three NC state representatives and one state senator were found to have matching names and dates of birth with registered voters in other states.
So while the original article used enough weasel words that it's not technically wrong, the scale of fraud it described is grossly exaggerated.