There are walls to the ceiling separating the two duplex units.
There is a dividing wall between the two duplex units. Therefore the loft of one unit is ONLY open to this same unit. One unit can NOT see into the other unit. The dividing wall is a two piece wall that meets in the middle and overlaps. This allows for thermal expansion and contraction. I.e. it is staggered. This is a detail that is probably unimportant to you at this point, but it may be helpful to understand how such a wall does not violate the requirement that “NO interior walls can be built that extend between two opposite arches”.
AUG