Dual RA Failure is a tricky one, it doesnt tell you that you cant arm the approach mode thus you have to fly it like a localizer approach. Also its one of the failures that takes you from Normal Law to direct law upon gear down, so you have to know to use conf 3, ref plus 10 and add 20percent to your landing distance. Also your AP trips off so you have to hand fly it. The reccomended flying reference is the bird.
Hope this helps