Shared stairwell side by side duplex

[TJ Sinn]

My wife and I are purchasing a side by side duplex right now that is three beds and 1 1/2 bath on each side. The top of each unit is 2 bedrooms and a bathroom with kitchen. The units have separate entryways but in the back they have a shared exit along with a shared stairwell to the basement.

When you get to the bottom of the stairs each side has its own door to go into that brings them to their third bedroom and 1/2 bathroom, along with their own laundry and basement living room.

Has anyone dealt with this before where there is a shared stairway and you would have to use it to get to your lower bedroom and laundry area? My wife and I are wondering if it makes sense to add a spiral staircase to one unit so they have a fully private unit top and bottom and no shared area. We would leave the entry doors at the bottom of the stairs so for move in and move out they could access a door from the main staircase to move items in and out.

Does it make sense to try to add a separate stairway? Or have people noticed no change in rents for tenants to have the shared stairwell area?