One for breathing the other for bean storage

One always has better boogers

Why not 3 then?

We have stereo smell to help with locating smells. There's also the nasal cycle. One nostril/sinus handles most of the airflow, then they swap (the sinuses are separate until they get to the throat). That way one can recover moisture, plus some smells are more easily detected with fast airflow and others with slow. So the nostrils functioning differently gives us a broader range of odor detection. What else? Umm, bilateral symmetry and redundancy is useful.

Yeah, if they could both work at the same time though, that'd be ideal.

If you do enough cocaine, you can end up with one nostril. It happened to a British TV celebrity in the 90s.

So that we know which side to lay on because one is clogged?

Bilateral symmetry, hox genes.

So when the crayon gets stuck up one nostril, we can still breathe and run for Congress.

So one of them can be always fucking blocked.

my homebrew theory is its also so you can smell directionally.

Don’t develop a cocaine-perforated septum, kids.

"Dad said nope, that it's the one hole too far, you pervs"

Is that similar to why we have a pee hole and a poop hole instead of one big combination hole?

You are one big hole?