Hi @Oana Palade,
Thank you for dropping by here in the Community. I'm here to help you manage the Customer list in QuickBooks Online.
Currently, an option to correct the current customers automatically is unavailable. The only workarounds are to merge them one by one or delete duplicates manually.
In case you need the steps on how to merge, here's how:
- On the left navigation bar, click Sales.
- Select Customers.
- View the customer profile you don’t want to keep.
- Press Edit.
- In the Display name as field, enter the name of the customer profile you want to keep. The names need to match exactly.
- Select Save.
- When asked if you want to merge the two profiles, select Yes.
Additionally, I've attached an article you can visit to learn more about the information you can upload to QuickBooks, as well as the import limitations: Common questions about importing data to QuickBooks Online.
Drop me a comment below if you have any other questions about importing data or managing customers. I'll be happy to help you some more.