Why do unlimited Taskbar-Icons appear?

Due to limited access to the registry for the logged in user, it may occur that multiple GO Contact Sync Mod Icons appear in the task bar.

To resolve this problem, please do this:
1. open program "regedit.exe" and go to HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
2. right-click on "Run" and than select "Permissions..."

If your username is missing in that list, this might be the problem:
3. Click on "Add..." and add your username
4. Tick the checkmark on allow "full access"

Reference: https://sourceforge.net/p/googlesyncmod/bugs/513