Banks have nothing to do with the transaction. I am afraid that even if the amount is not withdrawn, banker can not refund that amount. The two individuals should settle the matter within themselves and there is role on part of the bank in authentic transaction.
Any transaction if it is by mistake, it has to be established, and amount should be recovered legally if the other customer in whose account amount credited failed to refund the amount.
I am sorry, but I personally feel that member is not coming out with facts as such transactions was highly improbable. My presumption is that amount was paid to the concerned account voluntarily with his own will, and when disputes arose, he wanted to seek refund stating that it was emitted by mistake. This is not easy issue to recover if both payee and drawer are having some sort of relationships.
There are similar cases decided in Supreme Court in Jammu and Kashmir bank cases, where in Accountant General paid some amounts to the employee, and when the bank refunded the amounts on it's own to drawer by debit to account SC has decided that once the amount is credited, bank is not having any powers to debit to the account unless it is on their own mistake or on fraud.