I have a Macbook Pro and when I click with the trackpad, it will occasionally act like a double click. This happens whether I physically click the trackpad or if I just do a tap to click. I have tried changing the double click speed to no avail. It might be a hardware issue, but the fact that it happens when I tap to click leads me to believe it is at least not a mechanical issue (still possible an electronics/cable issue with the trackpad). I have also reset the NVRAM and the SMC (not sure why it would be an issue with those but I'm attempting everything). I'm on Yosemite.