(AP) A software glitch that indicated scores of voters showing up at the polls had already cast ballots has led to voting delays in one of North Carolina’s most heavily Democratic counties.

North Carolina Board of Elections lawyer Josh Lawson says officials in Durham County quickly concluded that there was a problem with their electronic poll books and began relying on paper rolls to confirm voter registrations. Attempts to vote twice are rare.

Lawson says there’s no indication “nefarious activity” caused the computer problems. Rather, he said it could have been a failure to clear out caches of votes cast during the primaries.

About two dozen other counties using the same software have not reported problems.

Lawson said those in line when the polls close will still be allowed to vote.