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I've got you covered, chris229.
When you send an invoice to a customer, make sure to mark the invoice closed and paid once you receive the payment. This is to avoid confusion and prevent you from resending it.
From the Received payment page, you can choose and link the invoice to mark the transaction as paid. To do this:
For additional information, you can click this article: Record invoice payments in QuickBooks Online.
Another instance would be to check if there is a recurring invoice set up the reason why invoice information is the same and was sent on different dates. You'll want to delete it if you think it's unecessary.
To learn more about managing scheduled transactions, see this article: Edit a recurring template.
However, if you're referring to duplicate invoices sent to your customer, you can review your sales by following the steps below:
With this article, you can learn more about customizing, attaching files, and emailing sales forms to your customer within QuickBooks Online: Email and customize sales form.
You're always welcome to comment below if you have other concerns or follow up inquiries about managing transactions in QBO. I'm just around to help. Take care always.