Two Norton icons in my System Tray

For quite some time now I have been getting two Norton system icons in my System Tray.  I presume that two copies of Norton 360 are running simultaneously, and my system is being slowed down by them clashing.  Recommendations online suggest that I clear this by restarting the machine, which I have done, but this only works sometimes and besides, I'm not prepared to continuously restart.

Help! How can I stop this situation happening?

Many thanks for any assistance available.