I recently updated Google Chrome and also encountered this problem.
After doing a reboot I noticed that Google Chrome now appears twice searching for it in slingshot
Attaching a screenshot
The way I remove unwanted icons is use the program menulibre.
sudo apt-get install menulibre
That will give you a menu editor.
Open the Menu Editor and search for Chrome. Hide the icon and save your settings. Close and reopen the Application Bar and see if your duplicate is gone.