Hi there, @omar7. I'm here to lend a hand. 

We haven't received any reports regarding any issues about duplicate customers displaying in the search field in QuickBooks Online (QBO).

When QuickBooks has unexpected behavior, let's perform some basic troubleshooting steps to fix the problem since sometimes cache stored up in the system can cause unexpected behavior in the product. You can start by opening a private (incognito) window. Using a safe browser and accessing the program from there can usually fix the issue.

Here's how to open it:

• Chrome: Ctrl+Shift+N
• Firefox: Ctrl+Shift+
• Safari: Command+Shift+N

Once done, try open your QBO account again and search customers. Check to see if it works. If yes, then your main browser causes this kind of issue. To ensure this doesn't happen again, it's a good idea to clear the cache of the browser you're using.

However, if the issue persists, I recommend using another supported and up-to-date browser. 

Please keep me posted how things go on your end. I want to ensure this gets resolve for you. I'm always here to help. Take care. 

I have tried as you said but it's still there. Every use of facing this issue. Looks like more to do with our database being corrupt. 

I appreciate you for trying the troubleshooting steps above, omar7.

At this time, I recommend reaching out to our Phone Support team. We have agents there that can open your account and verify the issue further.

You can contact us by clicking the ? button and then entering Talk to a human. Then, select Live chat.

I'm around if you need help. Keep safe!