Dominion did not immediately respond to a request for comment.
In Antrim County, Mich., unofficial results initially showed President-elect Joseph R. Biden Jr. beating Mr. Trump by roughly 3,000 votes. But that didn't seem right in the Republican stronghold, so election workers checked again.
It turned out that they had configured the Dominion ballot scanners and reporting software with slightly different versions of the ballot, which meant that the votes were counted correctly but that they were reported incorrectly, state officials said. The correct tallies showed Mr. Trump beat Mr. Biden by roughly 2,500 votes in the county.
In Oakland County, Mich., election officials also spotted an error after they first reported the unofficial counts. They realized they had mistakenly counted votes from the city of Rochester Hills, Mich., twice, according to the Michigan Department of State.
The revised tallies showed that an incumbent Republican county commissioner had kept his seat, not lost it. Oakland County used software from a company called Hart InterCivic, not Dominion, though the software was not at fault.
Both errors, which appeared to go against Republicans, spurred conspiracy theories in Conservative corners of the internet. That drew a response from Tina Barton, the Republican clerk in Rochester Hills, the city that had its votes briefly counted twice.
"As a Republican, I am disturbed that this is intentionally being mischaracterized to undermine the election process," she said in a video she posted online. "This was an isolated mistake that was quickly rectified."