My job involves computational linguistics, with a focus on the Arabic language. I’m not a linguist by training, so I was fascinated to learn that Arabic has a dual number in addition to singular and plural. I’ve been told it’s not the only language that does, either.
Oh it’s very common. Even ancient Greek had a dual. And then you get inclusive and exclusive pronouns…
In case anyone wants to read further… some languages are even more complicated in how they apply the “dual”.