I'm presuming your court date was with the gunsmith? How did it come out? People want to know. If your buttstock was a PROPER replacement, it should have nothing do do with it doubling. If not, there could be pressure from a tad of wood pressing on the sear which will cause it to trip from recoil caused by the right barrel going off. You didn't mention if this was a single trigger or double trigger model. A single trigger gun could have other problems. The only other simple cause is a very light trigger pull on the second barrel being jarred off by recoil. The above info, from Dunlap is also good and should be followed.