All you was doing was doubling the gasket thickness. This why it don't work most times. It takes making wedge gasket as you need to apply extra pressure only the area of non-contact.I have had those not work with the double gasket trick. I wind up using a very light coat of The Right Stuff sealant on both sides of the gasket. Let it set for about 20 mins then assembling and not overtightening it. Works with the warped covers too.