Thanks for the screenshot, @Paolo_S.

I've got you covered in handling the duplicate accounts in your Chart of Accounts (COA) list.

First, you can run the Audit Log to know if someone created the said accounts. 

Here's how to do it:

1. Click the Gear icon, and then choose Audit Log.
2. Select the Filter drop-down, and choose the All Users and the desired date.
3. Tick the Show only these events radio button under Events.
4. Select the Lists option. 
5. Choose All Transactions from the Show drop-down.
6. Click Apply.
7. You can click View in the History column to open the audit history. This way, you'll know who made the change and what they did.
   

If no one made changes to your COA list, then this is likely a browser-related issue. To fix this, you can use a private browser (incognito) when opening QuickBooks. This session disables the corrupted cache in your browser and prevents unexpected QuickBooks Online behavior. 

Based on your screenshot, I can see that you're using a Safari browser. Thus, you can press Command + Shift + N on your keyboard to pull up a private window.

After that, sign in to QuickBooks and review your COA list again. If can now able to see the right accounts, you can clear your regular browser's cache. This process helps delete corrupted files so the system can start a clean slate.

If the issue persists, you can use another device or supported web engine instead. Another option is to utilize the browser health checkup tool to see if your browser is compatible.

The good thing is, you can run an Account QuickReport to review your account's transactions. To do that, go to the Accounting menu, and then click Run report.

Stay in touch with me if you have more questions about handling your COA in QuickBooks. I'd be glad to extend a helping hand always.