payzippy/zen-cart-plugin — pull request #2 by vkd1980 (2014-04-16 11:02:48+00:00)
Title: Update payzippy2_process.php

Hi,

You are actually posting response to Merchant site,but in module you are using $_GET. while using this charging response will not get all the params to match hash and will lead to pop the error "Duplicate Transaction Detected. Your transaction has failed.". as there is no transid

working successfully after changing it in myzencart site