Hi there, brittanynaturalf.
Thanks for checking in with us. I'm here to help you fix duplicate invoice numbers in QuickBooks Online (QBO).
If it's a duplicate invoice, you'll need to delete it. However, if it's only the invoice number that has duplicate, you have the option to edit the invoice number.
Let's first locate the duplicate invoice number in QBO. Let me guide you how to get there:
Here's an article to learn more about the different ways on finding duplicate invoice in QBO: How to find duplicate invoice and other transactions.
To prevent duplicate invoice number in the future, we can customize your Accounts and Settings preference.
There you have it. Always feel free to drop by again anytime you need help. You have a wonderful day.