Add duplicate check into notificaiton processing and fix formatting

Model/Notification.php

@@ -86,11 +86,12 @@ class Notification extends \Magento\Framework\Model\AbstractModel
      * @param $eventCode
      * @param $success
      * @param $originalReference
-     * @return bool (true if the notification is a duplicate)
+     * @param null $done
+     * @return bool
      */
-    public function isDuplicate($pspReference, $eventCode, $success, $originalReference)
+    public function isDuplicate($pspReference, $eventCode, $success, $originalReference, $done = null)
     {
-        $result = $this->getResource()->getNotification($pspReference, $eventCode, $success, $originalReference);
+        $result = $this->getResource()->getNotification($pspReference, $eventCode, $success, $originalReference, $done);
         return (empty($result)) ? false : true;
     }