Do you mean it is shooting twice per trigger pull? Or, do you mean that you can pull the trigger twice and shoot twice?
If it is shooting twice on two trigger pulls (operating in semi), then the bolt is resetting far enough to catch and also to open the on-off and allow the front chamber to charge. The wave spring should prevent this, especially with the shorter worn bolt spring causing the needed bolt stick. If this is the case, you need to find out what isn't preventing the bolt from resetting. I suspect this is not the case and the problem is actually the next version.
If it is shooting twice per trigger pull, then the on-off is most likely opening prematurely or leaking which is charging the front chamber and causing the bolt to fire again as it attempts to reset. Ideally, the wave spring prevents the bolt from resetting and doesn't allow the sear to rotate forward to open the on-off. If the on-off can open without the sear rotating forward, then the on-off is probably leaking, or your pin is too short. The leak is the most likely scenario and can probably be solved with an oring change.
Except for the Automag in front, its usually the man behind the equipment that counts.