According to a Houston Chronicle report, that seems to be the problem in at least 16 Texas counties, where a review of their records by Judicial Watch showed more voters on the rolls than there were actual voters in the county. One of the biggest discrepancies (as a percentage) was in Loving County, where there are only 40 eligible voters, but 65 on the voter rolls.
As the article notes, this has been a problem since the 90’s, because many counties, particularly rural counties, lack the time and manpower to regularly update the voter rolls, which is an issue that I have discussed before (here and here); however, there are other factors as well, such as “snowbirds” and college students who vote in one county but are considered residents of another county by the U.S. Census.
The one serious issue (imho) mentioned in the article was that of people who return to a county to vote even if they live somewhere else. This was an issue in a recent election contest in Texas, where there were some voters who lived in a different county in Texas, but continued to vote in Travis County.