The bank accidentally paid tens of thousands of people on Christmas Day and is trying to recover about 130 million pounds.
Many customers of rival banks received the mistaken payments. The other banks are being asked to help recover the money.
The deposits could look like regular payments to recipients because they were duplicate of payments that had already been made.
The money for the second payments was not from customers.
The bank said that some payments from corporate clients were duplicated on the recipients accounts. We will be working with many banks in the UK to recover duplicated transactions, and none of our clients were left out of pocket.
According to The Times of London, people with accounts at many banks, including HSBC and Virgin Money, were among those who received the incorrect payments.
The banks where people received the payments have been asked to help recover the money.
The company said it was using its own processes to recover money that was paid in error. The banks were not sure how they would deal with customers who had already spent money.
The British arm of the Spanish bank has more than 14 million customers. In the third quarter of this year, the British operation reported profits of $929 million, up from the same period in 2020.
In May, the bank apologized after a technical problem left some customers unable to use banking services.
It's rare for banks to deposit millions in error, but mistakes like this can be costly for those who receive the money.
A woman who worked for the emergency services was arrested on fraud and theft charges in April after she bought a house and used some of the money that a financial services company accidentally deposited into her account.
Two sisters from England were sentenced to prison in February 2008 after they spent over a hundred thousand dollars on a mistake by a bank.