Note: This requirement is a contributor to US apartments being ugly. Depressing line corridors, and only one side of windows unless you're in the corner. Other countries don't have the double stairway requirement, and are prettier as a result.

A particularly dramatic example of this is Baltimore's Bromo tower https://www.bromoseltzertower.com/about/virtual-tour It was turned into some sort of artist studios, and as a minor architecture nerd i was having fun looking at the floor plans. The two staircases right next to each other confused me. Turns out it is that same requirement to have two independent stairwells and that was probably the least worst place to put them. Still stupid however.

Are the two elevators a code requirement as well?

See also: The Newby–McMahon Building https://en.wikipedia.org/wiki/World's_littlest_skyscraper Where they sort of want to use the upper floors. but it can barely fit one staircase, two would take up the entire floor, a building code quandary.

>This requirement is a contributor to US apartments being ugly.

US apartments look ugly because the IBC has been picked over by every flavor of money grubbing business interests masquerading as concerned do gooders. Once you filter out all the options rendered financially noncompetitive by each of their bought and paid for rules there's only a few paths to a viable building. You might have a dozen megacorps buying windows from a dozen suppliers but those dozen times dozen theoretical options are the same thing in practice because that's what it takes to hit Leed Platinum (TM) or whatever.

Seriously. Go watch some 80s/90s movies that were set in the then present day. Those cube farms have more diversity of style and material than anything today.