How are you triggering the forward or reply? There is a known issue in GroupWise 6.x.x (I’ve not looked to see if they’ve fixed it in 7 yet) that causes the reply/forward events to be fired twice if you use the Reply/Forward drop down button menu from the item view toolbar. It fires only once if you reply/forward _without_ using the drop down menu button. Unfortunately, as a third party we are powerless to detect and work around this bug.
Novell have certainly been made aware of this issue.