There are two reasons why a duplicate billable expenses transaction is showing, bgoon. Allow me to guide you through each possibility to help resolve this efficiently.
 

Firstly, changes made to the billable expense or in the invoice could cause them to be unlinked. This could lead to the expenses not being invoiced.

Second, it is being created or manually entered into the software. If you want to know who made the changes, you can follow these steps:
 

1. Navigate to the Gear icon.
2. Go to Audit log.
3. Filter drop-down menu.
4. Utilize All users, Date, and Show all events.

If you need to check your transactions or make changes, you can do it directly in the account register. Refer to this article as your guidance: Find, review, and edit transactions in account registers in QuickBooks Online.

Once you have reviewed them and confirmed the duplicate, and if you wish to delete it. Here's how:
 

1.  On the left panel, go to the Transactions menu.
2. Click Chart of Accounts.
3. Choose the appropriate account, then click View Register. 
4. Locate the duplicated transaction.
5. Click the Delete button.
6. Yes, to delete the transaction.

To ensure your bank and QuickBooks balance align accurately, check this article for the details: Reconcile an account.

Should you have any additional questions regarding the appearance of a duplicate billable expenses transaction, notify us. We are always here to assist you right away in identifying and resolving your concerns efficiently. Have a good one.