Barclays says it has fixed a problem that caused duplicate payments across an undisclosed number of customer accounts.
A spokesman for the lender confirmed that the bank detected a "small number" of duplicate debit card payments on Monday morning, but later said that the issue had been dealt with.
"I can confirm that this matter has now been resolved and all customers have been refunded, with no one left out of pocket," the spokesman said.
The bank has not provided any details on what caused the problem.
It is the latest payments debacle to affect consumers this week, after a problem with Asda's card machines on Sunday caused long queues at checkouts across the country. The supermarket later apologised to customers and said it was working on fixing the issue.
Other banks have seen customer services affected this year, including HSBC, which was hit by a denial-of-service attack that temporarily shut down its online banking service in February.
In April, Barclays' customers complained that they were unable to make payments from their accounts, an issue for which the bank later apologised and attributed to a routine systems update.
It marked Barclays' second payment systems glitch in six months, following a similar problem in October 2015.