You need to check your installation again to ensure that the striker resets every time the slide is racked. The parts sound like they are out of alignment. Once you get that fixed, try this and let me know how it goes - when you are at the range, pull back the trigger deliberately and keep it held back until the gun cycles completely. I believe that with a lighter trigger pull, if you pull the trigger lightly with your finger, the recoil of the gun actually causes your finger to bounce, creating the doubling effect. Try consciously pulling the trigger all the way back towards the frame / grip, see if that eliminates the doubling.