Duplicates in reports can be a little tricky. But don't worry, I’ll provide you with tips to help you organize your report data, accounting.
If you’re working with a transaction-based report and notice the duplicate rows are actual entries, you can click on the amount to open it. Then, review the transaction to confirm if it’s a true duplicate. You may delete the unneeded entry.
If its the row headers, we can use the Filter option to choose which specfic exactly which data to you'd like to display on the report. This will help unnecessary repetitions.

On the other hand, if you’re referring to the vertical section in the report, you can remove the duplicate by unchecking the box in the Columns panel.

I would also appreciate it if you could share which specific report you’re reviewing in QuickBooks Online. Knowing this will help me tailor a solution that addresses the issue more effectively. Feel free to add more details, so we can get this all sorted out for you.
Don’t hesitate to visit the Community again if you have any other concerns.