Just beating a dead horse now but to be explicit relating to your issue you can just remove current.update() to solve your problem. I tried it without and it functions fine the way you have it set up. (from my quick testing anyway) The current.update() will cause it to update again and create the duplicate in your log. In the best practices which has been quoted and referenced it says never to use current.update()

http://wiki.servicenow.com/index.php?title=Business_Rules_Best_Practices#gsc.tab=0