You lucky dog! You have a double tap 1911?!?! lol kiddin.
Double fires are usually not a mechanical defect; they are a shooter defect. Some shooters begin with a proper grip, but as they shoot their string, they begin to relax their grip. Are you limp wristing it? If not, which I'm guessing you would not be limp wristing... (just throwing it out there).. thennnn..
I'm thinking damaged sear or hammer contact surfaces, or it could be the overtravel screw that's in too far? dunno.