Hi there !
You can use the excelify app to get rid of your duplicate orders. Follow these steps:
1. First you have to download it from the Shopify app store. Then, go to your Shopify store back-end. Navigate Apps -> choose excelify -> export.
2. Choose Orders to export to Excel file.
3. Sort your exported file by Title and Handle
4. Make the formula that shows duplicated row of the same title
5. Filter Excel rows to show only the duplicate rows
6. Copy the columns ID, Handle and Command to the new sheet
7. Import the file with Excelify