What is the meaning of "Such a BankConnection already exists"?

The message “Such a bank connection already exists." is returned by our API due to our bank connection duplicate detection. The detection is based on the bank ID and the set of stored bank credentials. If the user already has a bank connection with identical bank credentials, the service will be rejected with the duplicate error message.

The duplicate detection is only possible for banks that do not use the redirect approach. In the case of a redirect, the bank provides us with the accounts directly after authorization of the user and a duplicate comparison is not possible.