"...election workers write an identifying number on the ballots of voters who vote by mail or during the in-person early voting period. This is a special number assigned to each ballot and voter. This number allows the ballot to be retrieved and not counted if necessary due to a voter challenge, such as if the voter dies before Election Day or votes more than once. See Retrievable ballots (N.C.G.S. § 163-166.45).
The number can also be used to retrieve ballots in the event of a successful election protest, such as if several voters are given the wrong ballot style and the margin for a contest is less than that number of voters."
I went back and re-read the links, as well as Bob Orr's comments, and it seems like NC uses a confidential system for "retrievable ballots" for most (but not all) mail and early votes. So, if Griffin were to prevail on his challenge, he could theoretically get certain votes tracked and uncounted.