What is this error "Duplicate Document Number Error:\n" + "\tDuplicate Document Number Error : You must specify a different number. This number has already been used.

Hello there, @user05423.

You can manually delete those duplicate transactions in QuickBooks. Let me guide you how.

Here's how:

1. Find and open the duplicate invoice.
2. Click More at the bottom.
3. Select Delete.
4. Click Yes.

You can also check out this article to learn more about deleting invoices and other transactions: How to void or delete an invoice or other transactions.

Please keep me posted if you have any questions. All the best!

How do you find the duplicate invoice if it does not provide the invoice number? 

Good afternoon, @user05423.

I'm happy to help you locate duplicate invoices.

If you need to check for duplicate sales (invoice, sales receipt, etc.) numbers:

1. Select Sales from the left menu.
2. Choose the No. column to sort it.
3. When the Sales populate, it toggles the numbers in ascending and descending order.
4. Check for duplicates.

If you need to locate other types of duplicate transactions, here's an article to go by: How to find duplicate invoice, estimate, or sales receipt numbers.

If you run into any issues, just reach out. We are always here to help.