I had to check - it is one ply. I hadn’t even noticed, so that hasn’t been a problem for me. All I know is the Scott Four Pack lasts longer in my house than on on Charmin 8 pack. It may be ‘quilted’ and two ply, but its wrapped around the roll like cotton candy, its so loose.
If its one ply then you need to fold it over, so it actually half the bargain you thought. Northern Quilted is double ply.