Hi there, 1929Chrysler.
Your duplicate deposits are coming from your bank transactions. Instead of using the Match option you've added them to your register.
It's right that you've deleted them and they showed up on the Banking page specifically the For Review tab. So they won't cause duplicates again, you can select them, click on Batch Actions and choose Exclude Selected. This will transfer them from the For Review tab to the Excluded tab.
Here's what you can do moving forward: When you deposit multiple payments at once in your actual bank account, you also need to do that in QuickBooks. Then, when the actual deposit is downloaded on the Banking page, you can match it with your deposit in QuickBooks. No need to split them. In this process, nothing will be added, you'll just match them. Therefore, you'll not incur any duplicate deposits.
On the other hand, I'd only recommend using Split when you add transactions that were never created in QuickBooks. The split doesn't have a Match option, only Save and Add. So if you have invoices which will increase your bank resister when paid, then you add the split transactions which will also increase your bank, you'll double your deposits.
If you have other questions, you can always go back to this post. Have a good day!