My Logitech G500 sometimes did double-clicks instead of single-clicks. Problem was a little copper plate inside the mouse. If you want to fix it, too, watch the video or look at the diy page:

http://www.overclockers.com/mouse-clicking-troubles-diy-repair/

Closer look to copper refitting: https://www.youtube.com/watch?v=AbIuWNYP-kk