Hi stefaniad.
Creating a journal entry for your account payable is a great way to help adjust and keep your accounts correct. I'd be happy to help you with this.
The main reason you wouldn't be able to have two account payable accounts in one journal entry is if they are for different currencies. Normally QuickBooks Online only has one account payable account and it'd be in your home currency so if you have two that are using different currencies the system wont accept it. To get around this you may need to make another journal entry for the second accounts payable account.
If you have any questions let us know and we'd be happy to help.