Northern Ireland MPs Iris Robinson and her husband Peter both tried to claim for the same £1,223 expenses bill on the same day.
Mrs Robinson, who once described homosexuality as an “abomination”, was exposed in the latest round of expense receipts published by the Daily Telegraph.
The Democratic Unionist Party MPs have come under scrutiny for their financial affairs before, with a tabloid newspaper reporting last month that they claim almost £600,000 a year in salaries and expenses.
The double claim was rejected by officials, as was a claim for a total of £10,860 in mortgage interest payments made by the couple – covering five months – because they did not provide mortgage interest statements as proof. It was not clear whether the money was paid to them or if they eventually submitted evidence of the interest.
Between 2004 and 2008, the couple claimed a total of £159,208 on their east London flat, most of which went on mortgage interest repayments.They bought the flat in 2001 for £450,000.
They also claimed £30,525 for food between 2004 and 2008, reaching the £400 limit most months.
In response, Mr Robinson described the double claim for the £1,223 bill as “an innocent mistake”.
He said: “The two claim forms were prepared for the signature of my wife and myself by the same person. They are signed separately and then sent together in the one envelope. Anyone in the fees office would have been dealing with the claims together and inevitably would have noticed the innocent mistake. It is clear that this one duplicate entry over many years was an innocent error and happily was spotted.”
He added that the £100 per week claims for food were “not unreasonable”, although he said none of the couple’s children had spent “more than half a dozen nights in the apartment over the years”.
Mrs Robinson earns £63,291 for her position as an MP, £24,296 as an Assembly member and as chairwoman of its health and social services committee and £9,550 as a councillor for the Castlereagh borough in Northern Ireland.
Mr Robinson takes home £63,291 as MP for East Belfast, £71,434 for his role as First Minister plus a third of the £43,101 salary for being an Assembly member because he is also an MP.
They also claim more than £150,000 for the salaries of their staff with Mr Robinson employing their daughter Rebekah as office manager and private secretary and son Gareth as parliamentary assistant.
Mrs Robinson employs their other son Jonathan as office manager and daughter-in-law Ellen Robinson as part-time secretary.
Earlier this year, police said Mrs Robinson would not be prosecuted over remarks she had made about gays.
Speaking to the Belfast Telegraph last summer, she said: “I cannot think of anything more sickening than a child being abused. It is comparable to the act of homosexuality. I think they are all comparable. I feel totally repulsed by both.”
She also suggested that there are therapies to “cure” people of homosexuality, saying: “I have a very lovely psychiatrist who works with me in my offices and his Christian background is that he tries to help homosexuals trying to turn away from what they are engaged in.
“And I have met people who have turned around to become heterosexual.”
Shortly after her outburst, Mrs Robinson’s son Gareth was photographed kissing a man and sitting on his knee at a Belfast party.