The Virginia attorney general’s office said Thursday that it is investigating “several possible cases of duplicate voting” uncovered after a comparison of the commonwealth’s registration rolls against voter lists in 21 other states.

State Board of Elections spokeswoman Nikki Sheridan said the board requested the investigation Wednesday. The probe was prompted by results of a voter registration database check that turned up more than 308,000 duplicate registrations in Virginia.

Of those, more than 97,000 were listed as having voted in recent elections in Virginia.

Caroline Gibson, a spokeswoman for Attorney General Ken Cuccinelli II (R), confirmed Thursday than an investigation is underway. But she declined to comment on how many potential cases of duplicate voting were detected in the cross-check, citing the ongoing investigation.

Last year, Virginia joined several states — including Kansas, Arizona, Georgia, Oklahoma, Indiana and Tennessee — in an interstate cross-check of registration databases with more than 85 million voter records. Sheridan said the partnership serves as a way to maintain and update voting records.

The reason for the duplicate registrations could be explained by a person moving to a different state, attending college or serving in the military. Sheridan cautioned that such findings do not necessarily constitute voter fraud.

Like other states that have Republican leadership, Virginia has focused on voter and election laws in recent years. Supporters have said the steps are needed to protect the integrity of the voting process, although little evidence has been produced to point to widespread problems at the polls.

Most Democrats have opposed such laws, saying that they burden the elderly, poor, minorities and students, and that the measures aim to suppress voter turnout in some communities.

In 2012, Virginia passed a law requiring voters to present identification to cast a ballot, although the ID did not have to include a photograph. Last month, Gov. Robert F. McDonnell (R) signed legislation that will require Virginians to show a photo ID before casting a ballot.

The law must first be approved by the U.S. Justice Department and could be in effect in time for elections in 2014.

McDonnell also ordered the elections board to conduct voter outreach to educate residents on the ­changes and help those who lack photo identification to register.