I have recently switched to XUbuntu (14.04) and I have noticed that sometimes a mouse click is fired twice.
E.g. I CTRL click a link and two tabs with the same content are opened in my browser. It's not behaviour I can reproduce consistently and seems to be random (to me). I also don't know of a good way to inspect the behaviour properly for debugging purposes. I have checked the double click time setting but this doesn't seem to have any impact on this.
I also run XUbuntu (13.10) in a VM on my MacBook Air and this behaviour seems to absent there. At this point in time I can't really tell if this is related to the distribution or the fact that it runs in a VM.
Any insights greatly appreciated.
The multiple click problem has happened to me a couple of times since now; in both cases was a faulty mouse. My opinion is that the quality of the switches in most modern mice is at least questionable.
Check the mouse in another machine with (possibly) another operating system.
If you can, try to blow the mouse interior with compressed air (there are electronic-grade bottles around). That solved my problems once.
If the problem persist just on your computer/operating system, now it's time to search for a software problem.