I can help you get rid of the unexpected behavior, CharleneGSC.

Once transactions are deleted, they should no longer appear on your banking page. There are times that your browser is full of frequently-accessed page resources, causing QuickBooks Online (QBO) to act strange. 

We can do the basic troubleshooting steps to fix this. Access your QBO account using a private browser and try deleting duplicate transactions from there.

You can refer to these shortcut keys:

• Press Ctrl + Shift + P for Internet Explorer or Firefox.
• Press Ctrl + Shift + N for Chrome.
• Hold down Command + Shift + N for Safari.

If it works, go back to your regular browser and clear the cache to speed up the loading process of the QBO website and for the system to start fresh. Otherwise, switch to another browser if the issue persists.

I'd appreciate it if you'd update me on how the steps work. If you have any follow-up questions, do let me know. I'm here to help.