Can you use duplicate invoice numbers?

Welcome to the Community, Craig.

Let me share insights about invoices.

Yes, you can use the same number with your invoices. However, a prompt message will show up after you click Save.

Yet, having the same invoice might lead to discrepancies in your invoice report.

When you want to make eye-catching invoice forms, I'll drop an article for it: Customize invoices, estimates, and sales receipts in QuickBooks Online.

If a customer needs to pay on their invoices, you can receive and record the payments to track your account balance.

If you have any additional concerns besides invoices, please post them here in the community. Have a wonderful day!