Voter rolls suggest a record 4.2 million Missourians are eligible to cast ballots on Nov. 2, but officials acknowledged Tuesday the figure likely is inflated by people who are registered more than once.

There are fewer than 4.3 million voting-age residents, according to the most recent Census Bureau estimate. If Missouri's voter rolls were accurate, that would mean 98 percent of adults are registered to vote.

"It's inflated somewhat," said Betsy Byers, an election director, "but I don't know what to tell you as far as how much."

The inflated rolls could allow some people to illegally vote twice, Byers acknowledged. A more likely outcome, she said, is that many of the duplicate registrants will vote only once or not at all.

Missouri has no way to automatically update its central voter registration database when a resident moves to another city, county or state. And under federal law, it can take more than four years to remove a voter whose address cannot be verified.

In Colorado, officials said Tuesday that a last-minute crush of people signing up to vote, moving to a new precinct or switching parties has left tens of thousands of duplicate names on election lists.

Lisa Doran, a spokeswoman for the Colorado secretary of state, said about 90 percent of the extra names will be purged by Election Day as county officials conduct routine checks.

Nearly 110,000 people registered between Sept. 13 and Oct. 4, pushing the statewide total to nearly 3.1 million. But as many as 55,000 names appear in the secretary of state's list more than once, The Denver Post reported Monday.

County clerks are supposed to update their rolls monthly with data from the secretary of state, but not all of them do, Doran said.