Illegal and dangerous. What's happening is the hammer is not catching on the sear, so it follows bolt forward and impacts the firing pin. This can cause a Kaboom if the bolt is not fully locked when the firing pin sets off the primer.
Any time your firearm shoots two or more shots with one pull of the trigger, you have a machine gun. Possession of an unregistered machine gun is a serious Federal felony. ATF loves to convict people for this as it's an easy conviction and they get lots of press on it. Get this fixed ASAP!