Hi @LS_Smock –
With Plaid, you should be able to add accounts from any banks as long as they’re supported by them.
In the Sandbox environment, Plaid only returns two sets of Routing and Account numbers regardless of which bank is selected-- one for checking and one for savings. As a result, you’ll be able to add only two bank accounts in the the Dwolla Sandbox as well since we don’t allow a bank with the same Account and Routing number to be added twice. Perhaps that’s what caused the error? If you’re able share one of the funding-source IDs that was returned as the Duplicate Resource that already exists, I could take a further look to see if that’s the case here too.