Financial product &1 with no. &2 already exists

What causes this issue?

A financial product with the number selected by you already exists in
the database.

System Response

The system prevents a financial product from being entered more than
once with the same number.

How to fix this error?

Enter a different financial product number or select the change,
display, or delete function to continue editing.

Error message extract from SAP system. Copyright SAP SE.