Is it common for one skirtboard to be different in height than its opposing twin? I have 3 1/4" and 2 3/4" when measured from the wood floor to the top of the board. The appearance from tread nosing to the tops of boards looks identical but now that I have to add molding on the main floor at the top of the staircase I have to figure out what to do with differing heights.

Whoaa, more problems with the staircase. Off the top of my head I could see one remedy by adding a piece of the same material on the smaller stringer/skirtborad to balance out the difference. It would have to be tapered back from 1/2" to make it work.

Or, maybe the...nah that wouldn't work either. That's my thought too early in the morning.