[Larry the Gun Guy]

Or it could be your tight grip. I spent about $800 trying to fix my 12 gauge GHE Parker single trigger that was doubling. Then, some people on here suggested that I was gripping the gun too tightly and causing the second shot myself. I thought that was ridiculous, but it has never done it since I started holding the gun a little more loosely with my trigger hand. It may be worth a try.