Adding up

This is from Metropolitan across the lot that was the Dutch Mustard building. I was reading recently about the trend to add stuff to the tops of buildings and this what came to mind. I'll be interested to see if it matches or if it'll look like two buildings stacked on top of each other. What strikes me as odd is that if you look at the second photo it looks like the two pieces on the bottom of the addition are not the same thickness. Is the base building not level?