We are currently running Magento version 126.96.36.199 for both of our stores and we are processing payments through PayPal Payments Pro. Recently we changed the Payment Action for both stores from Authorization to Sale. While everything works fine on one store, the other store gives us the following error message on checkout.
"PayPal gateway has rejected request. Authorization has already been completed (#10602: Authorization completed)."
After doing some googling it seems like the issue is far more common when updating the status of a previously placed order. We however are getting this error on checkout and the order never gets placed. I've temporarily set this back to Authorization for the time being and everything is working again. But we would still like to set it back to Sale as it would save our bookkeeper a lot of time. Are there any other settings whether in Magento or PayPal that I should look into? I'm having a hard time figuring out how to fix this issue.