I'd suggest reviewing all the receipt entry in your QuickBooks account. This way, you can identify duplicate transactions by checking the information entered. To this, you can go to the Sales page or in the Account Register section. Please follow the steps below.
Sales page:
Click the Sales menu on the left panel. Then, All Sales section.
Choose the Filter drop-down button.
Select Receipt on the Type drop-down list and filter the other options.
Hit the Apply button all the receipts appear. From there, you can check all the details entered to recognize the duplicate receipt.
Account Register:
Select the Accounting menu and select Chart of Accounts.
Look and select the account you want to review. Then, click Account history under the Action column.
Select the Filter or the Funnel drop-down arrow. Then, choose Receipt in the Transaction Type drop-down list. You can use the Find field to search by amount, reference number, or memo.
Hit Apply.
Find the same information entered to identify the duplicate receipt.