Thanks for reaching out here. Welcome! Having duplicate invoices are most concerning, due to the imbalance it will cause in your books. QuickBooks Online, provides the option to void/delete duplicate transactions as necessary. However, deleting items cannot be undone, and can have a negative impact on other areas of your books. Although the '-cr', could indicate a credit being applied, it's difficult to determine the actual cause. For this reason, I feel you would benefit by contacting us outside of Community. This will provide us with the opportunity to work with you in real-time, and review your situation in more depth. This will also enable us to submit a ticket for further investigation if needed.
If you have any other questions, please reach back out. We would be glad to help!