I understand that you are unable to merge two accounts because they have different name types in QuickBooks Online (QBO), @postit.
Please note that you can only merge two lists of the same name type, for example, a customer list with another customer list, a vendor list with another vendor list, or any other list with another of the same type. In case you want to merge two different name lists, you can add a special character to the name, such as "Home Depot2", to differentiate it from the name used in another list.
I've also added this article for your guide in reconciling your account in the future: Learn the reconcile workflow in QuickBooks.
If you have any other questions in regards to merging, feel free just comment below. I'm always here to help. Enjoy the rest of your day!