Get a different mouse.
I was on my 3rd Performance MX mouse due to the same double clicking problem occurring after a few months of use. Long story short I brought a M705 Marathon Mouse and never looked back its on its 4th year and its still using the same batteries it came with! $19 at BJ's as opposed to the $99 I spent on the Performance Mouse at Newegg.
Trust me, I went through the rubber chicken solution they cave on their forums on taking out the battery, pressing all the buttons, even as to take the mouse apart, take apart the micro switch and clean it with WD40 and it still does the same thing.