Error: 'Transfers must not exceed the source amount' when creating a second transfer

Hi, I get this error when I try to create a second transfer with the same amount as the first one but a different `source_transaction`:

Transfers using this transaction as a source must not exceed the source amount of $57.00. (There is already a transfer using this source, amounting to $51.62.)

I’ve confirmed the two transfers have different `source_transaction` IDs. What’s odd is that, even though I see this error, the transfer still shows up as successfully created in the dashboard.