Mouse is registering two clicks when I only click once.

Praetorian Mage

I've had this happen with mice before, and I always just bought a new one, but this time it's a gaming mouse that would cost more to replace, and I'd like to avoid that if possible. So is there anything I can do?

dispatch.o

Take it apart and clean the switch. I've had to do it multiple times with my old MX518 and G5. They hide screws under the label and foot pads sometimes that requires you go digging to get the housing off, but they're really not too complicated once you get them open.

What type of mouse is it?

Librarian

Is it a Razer mouse? This issue seems to be a common problem with them, same happened to my Copperhead, same happened to friends.

Basically the material they use for the parts that push on the button contacts is too weak, so there will be a groove worn into it with some use and that causes the double-click issue.
It can be fixed by taking the mouse apart and filling the groove with superglue or some other material, but that is only a temporary fix.

DivideByZero

Yeah you'll probably have to get it apart and poke around inside to see what's going on with the contacts. It's not too hard but might seem overwhelming if you're not used to tinkering with stuff. Try searching Youtube for "[model] button repair" or somesuch, depending on the model there might be plenty of guides that show you exactly what to do.

Praetorian Mage

It's a Logitech G600.

I'm not normally good with fixing things, but I guess the worst that can happen is I break it and have to buy another one, which I was prepared to do anyway.

DivideByZero

Since your problem seems to be too much pressure on the contact switch, you could try just loosening the screws under the pad(s) at the front of the mouse and see if that helps.

Solvent

I have this exact same problem. I found this video, which is for the same make of mouse that I have. However, when I saw that it required some sort of electronics cleaner thingy (apparently) I said bugger it and bought a new mouse for 8.95, guessing that it might be the cheaper route.

This was a bad idea because the cheap mouse is much more inaccurate than the razer deathadder and now I realise I actually have to do some work to fix the problem...