And there is in this a rule:

If it mentions אחד..אחד from the point of view that both are one pair and this is known by the total number שנים – it will say both of them with the definite article ה. Like ויתנו לנו שנים פרים ויבחרו להם הפר האחד ואני אעשה את הפר האחד (Let them therefore give us two bullocks; and let them choose one bullock for themselves, and cut it in pieces, and lay it on the wood, and put no fire under; and I will dress the other bullock)¹⁴⁵.

footnotes: ¹⁴⁵ 1 Kings 18:23.

And if it will not say it from this point of view, it will say אחד...אחד without the letter ה.