Customers are being encouraged to check bank statements after a technical glitch caused transactions to be charged twice this week.
A Commonwealth Bank spokeswoman said the business was aware of the issue and would "be automatically removing these duplicates".
"We apologise for the inconvenience caused and are working to rectify this issue as quickly as possible and want to reassure customers that finalised transactions will not be charged twice," she said.
Members of Brisbane's Wynnum What! Facebook group raised the issue on Tuesday.
Customers had shopped at a variety of retailers such as Aldi, Woolworths and various petrol stations and chemists before discovering the double-up.
Belinda Clapson said her $150 fuel purchase had been processed twice, money she did not have to lose.
She said she had waited on the phone to the Commonwealth Bank for more than an hour.
Another customer Rickilea Fenwick-Molnár said a bill she paid also showed up twice.
The Commonwealth Bank spokeswoman said the reversals had been processed overnight.
"Customers should only be seeing the one transaction, which will be reflected in their balance.
"Any customers who are concerned are encouraged to get in contact with us."
