How to setup same bank for different supplier sites for US and UK

Summary:

We have a vendor that does business with both our US and UK BU's. The banking details are the same for each BU however, when paying invoices in US we must use ACH (ABA number) and when paying invoices in UK we must use (SWIFT). Whenever we attempt to update one BU the other BU updates as well. Can you assist on determining why that is? We need these bank accounts to have separate setups but for some reason when one site is updated both sites update

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