The Keens, both Labour MPs, represent constituencies in west London
Married MPs Alan and Ann Keen broke expenses rules by claiming for a second home when their other house was boarded up, a committee of MPs has ruled.
The couple did not live in their "main" home in Brentford, west London, for 11 months while it was being refurbished.
They must repay £1,500 and were accused of "a serious misjudgement" by standards commissioner John Lyon.
But MPs on the standards committee said they were victims of "bad luck" and had got approval from the Fees Office.
Labour MPs Mr and Mrs Keen represent the neighbouring west London constituencies of Feltham and Heston and Brentford and Isleworth.
Although their constituencies are in greater London, they chose to claim for a "second home" - a flat - nearer Parliament, as MPs were entitled to under old expenses rules.
But it emerged last year, in the weeks after the expenses scandal broke, that their "main home" - a house in Brentford - was unoccupied.
The standards and privileges committee said the couple had bought their second home in 2002 and for six years split their time between the flat and their Brentford home.
But in May 2008 work began to refurbish the house and they began to reduce the time they spent there.
Due to slow progress and "substandard work" they had it boarded up from December 2008 and did not return to stay overnight until October 2009 - during part of the period squatters moved into the house.
Standards commissioner Mr Lyon said they did not notify the Department for Resources - then responsible for MPs' expenses - until six months after it was boarded up.
The department advised them twice that owing to the "exceptional circumstances" of their case they could continue to claim for a second home.
But Mr Lyon suggested the couple should not have claimed for a second home when they effectively only had one property they could stay in and they should have sought advice sooner.
He added that they had effectively "received a personal financial benefit" - something that was "not in accordance" with expenses rules.
If they had not had a taxpayer-funded second home, they would have had to pay to stay in a hotel or rent another property, he said.
While he noted that they were advised twice by Commons staff that they could continue claiming, he pointed out that ultimately MPs are responsible for their own actions.
"A more rigorous examination of their circumstances might have led Mr and Mrs Keen to take a different view," Mr Lyon said.
While he carries out an investigation, it is up to a group of MPs - the standards and privileges committee - to rule on any punishment.
The committee said it took a "more lenient view" than the commissioner and while it agreed they had broken the rules - the "express approval" for their claims was a "very significant mitigating factor".
"It is quite clear that Mr and Mrs Keen suffered a long run of bad luck as they attempted at their own expense to improve their family home in 2008 and 2009," the committee said.
It ruled that "having allowed for a reasonable interval", they should have stopped claims for the last four months when their house was boarded up. The claims in that period amounted to £5,678.
But while the committee agreed the rules had been breached, it pointed out the couple had received approval for their claims, had suffered "difficult circumstances beyond their control" and there was no evidence they had intended to "procure for themselves a personal benefit".
It said full repayment would "not in our judgement be fair" and ordered them to repay £1,500 by the end of this Parliament.