Sally Richardson was looking forward to getting a $104 property tax relief check under a new program administered by the Maine treasurer’s office.

She wasn’t expecting to get two refund checks. But she did, and she still doesn’t know why.

“I’m wondering how many people received double checks and how they’re going to resolve this issue,” said Richardson, a homeowner in Stonington, on the southern tip of Deer Isle, overlooking Penobscot Bay.

State officials say she’s not alone, because a relatively small number of duplicate addresses were provided by municipal tax offices and slipped through the state’s screening process.

About 100 homeowners have received more than one refund check since the state started mailing them to 310,000 households across Maine in early January, said state Treasurer Henry Beck.

“It’s not a widespread problem,” Beck said. “We’re nearly done mailing out the checks and it’s gone smoothly overall.”

Still, Beck and his staff are counting on homeowners to be honest and notify the treasurer’s office if they receive more than one check. Otherwise, the office likely wouldn’t know if duplicate checks were cashed, even though officials took several steps to verify the mailing list before sending refunds, said Matthew Colpitts, deputy state treasurer.

Every homeowner was eligible to receive a $104 tax relief check this year if they had successfully signed up for a Homestead Exemption, which applies to primary residences where the owners have lived for at least one year as of April 1. The exemption reduces the value of primary residences by $20,000 when municipalities calculate property taxes.

The refund checks are part of a bipartisan tax package passed last year.

Sponsored by House Speaker Sara Gideon, D-Freeport, L.D. 1713 provides annual rebates of at least $100 to all participants in the Homestead Exemption program whenever there’s enough money in the Property Tax Relief Fund. The program receives 40 percent of any general fund surplus at the end of each fiscal year. This year’s refunds totaled $32.2 million.

The new program supplanted an income tax relief program established in 2012 under Republican Gov. Paul LePage and Republican majorities in the House and Senate.

That effort aimed to use general fund surpluses to reduce income tax brackets by a minimum of 0.2 percent the first year and 0.1 percent in subsequent years, but it never raised enough money to go into effect.

Money set aside in the income tax program was transferred to the new Property Tax Relief Fund, Colpitts said, and it could be several years before the fund has enough money to provide a second round of refunds.

The treasurer’s office has sent out thousands of refunds each week since Jan. 6 and will mail the final round of checks Monday, Beck said.

The office built the refund mailing list from lists of homestead owners provided by municipalities. The treasurer’s staff then compared the mailing list to various public records and culled duplicate homestead owners and other problems, Colpitts said.

Each municipality runs its own Homestead program, so the state was dependent on the lists that cities and towns provided, he said.

“The integrity of the law is very important to us,” Beck said. “We very much rely on the municipalities to send us accurate information about participants in the Homestead Exemption program.”

Despite the office’s efforts, some duplicates slipped through and were mailed. Some were reported by homeowners, others were noticed by office staff and corrected after the fact. Exactly how many is unclear, although Beck said it is about 100 and that he believes 99 percent of refunds were made correctly.

Homestead owners who received more than one check should report it to the treasurer’s office by calling 207-624-7477 or emailing propertytaxrelief@maine.gov, Colpitts said.

Sally Richardson was one of several Stonington homeowners who called Town Hall to report that she received more than one refund check, said Henry Teverow, a deputy town clerk.

A former state legislator, Richardson plans to write a note to the state treasurer when she returns her second check. She’s not sure exactly what the note will say, but she’ll likely have some stern advice.

“I have to think it through,” Richardson said. “It’s going to be nice, but I have to figure out what I’m going to say.”