Hi, I'm in the middle of papering some walls and used lining paper first. The trouble is that one of the walls wasn't plastered very well and the transition between existing plaster and new plaster is showing through as a raised section in the lining paper from the floor wall the way up to the ceiling. Now before I hang the final wallpaper, will it help at all if I apply a second sheet of lining paper to that wall to even out the bumps? 