My bank account was failing to sync. I followed online instructions by attempting to reinstate authorisation for the bank account. I now have 2 of the same bank account

Hello there, @karl-nicholson.

I appreciate the troubleshooting steps you've performed to fix the issue. Let's manually update your bank account to sync your transactions in QuickBooks.

Before we proceed, may I know what bank account is connected to your QuickBooks Online (QBO) account? Any additional information would be greatly appreciated.

Here's how:

1. From the left navigation menu, click Banking.
2. Choose Banking.
3. Click on Update in the upper right. QuickBooks will begin to update your account.

If the manual update doesn't sync your transactions, I'd suggest contacting our Phone Support Team. This way, they can further investigate this matter and create an investigation ticket if other users experiencing the same issue. 

Just in case you want to bring your bank transactions manually, you can import them by using Excel CSV files. For more guidance, feel free to check out this article: Import bank transactions using Excel CSV files.

You might also want to read this article to learn how to match transactions: Add and match Bank Feed transactions in QuickBooks Desktop.

Please keep in touch if there's anything else I can do to help you succeed with QuickBooks. I've got your back. Have a great day.