amzn/amazon-payments-magento-plugin — pull request #90 by islandskater43 (2014-11-13 23:50:31+00:00)
Title: Multiple Refunds Per Order

Currently if you try to refund multiple times on one order, you'll get an error back from Amazon, as the plugin is trying to use the same RefundReferenceID multiple times. This change introduces a random 4 character string into the RefundReferenceID to allow for multiple refunds per order.