Picture #11 shows the main laundry room with larger, side-by-side washer dryer. Picture #33 shows secondary laundry room with stacked.
Either the secondary is upstairs closer to bedrooms and is used for doing the daily clothes while the other is used for bigger items like bedspreads, or the 2nd is used by guests who are visiting for longer periods. Or if they had a live-in assistant, that was their laundry room.
It is an 8,000 sqft home, multiple options and reasons to have 2 laundry rooms.
Having laundry rooms on 2nd floor near bedrooms is finally catching on. It makes little sense to schlep up and down the stairs when a little forethought improves efficiency and convenience. Over next decade I believe more older homes will be retro-fitted with upstairs laundry, even if it results in stacked machines due to lack of space and connectors.