How can I add 2 payments to a single journal transaction? I made an error and had to make two payments out of my bank against 1 journal transaction

Hello, gbgardenology.

There can only one Accounts Receivable (AR) account in a Journal Entry in QBO. With that said, the option to add 2 payments to a single journal is unavailable.

I also recommend seeking expert advice from an accountant to ensure your books will be accurate. They can guide you on how to deal with recording those payments correctly in QuickBooks. 

Also, I got you this article that can guide you in reconciling your accounts accurately: Reconcile an account in QuickBooks Online.

I'm always here if you need more help with journal entries.