Why is my commercial card bank feed suddenly pulling in transactions from the cardholder card? they seem to be duplicating transactions?

Welcome to the Community space, @hugh-morrey.

The sub-account might be connected to your QuickBooks Online (QBO) account. That's why it's downloading your bank transactions. To resolve this, you can disconnect the sub-account.

Here's how:

1. In the left menu, click Banking or Transactions.
2. Go to the Banking tab.
3. Choose the account you want to change, and then click Edit (pencil icon).
4. Click Edit account info.
5. In the Account window, check the box next to Disconnect this account on save.
6. Click Save and Close.

For more information, here's an article you can check: Disconnect or delete accounts connected to online banking.

Once bank transactions are available, you can categorise your transactions.

Stay in touch with me if you have follow-up questions about connecting a bank account. I'm always around to help you.