As of late it seems like their is an auto double click bug
When purchasing items from a vendor(suck as mining picks) you are getting/being charged for 2 stacks instead of 1. I have also noticed the same to be true for karma vendors. It also happens when moving items around in your inventory. I went to move my chest of the mists and it automatically opened it.
I thought maybe it was an error on my end with my mouse settings but even after turning them all down it is continuing to happen. I asked if anyone else in my guild has experienced this, as I thought it was just me, and apparently it is happening to quite a few people.
Please look into this bug Anet…thanks