Matthew Poole and continuators on 1 Kings 3:18

18 And it came to pass the third day after that I was delivered, that the woman was delivered also: and we were together; there was no stranger with us in the house , save we two in the house.

So they could not be distinguished by their Age.

Therefore no Witness on either side: and although there might be some sensible difference to an exact observer between the features of the two Children; yet it is not probable that was much minded by the Neighbours: for though civil Women might assist them both in their Child-births, yet it is not likely they would afterwards converse much with them, as being persons of suspected fame, and the features of the Children, especially for so few days, night easily be so like, that it was difficult to discern the one from the other. And the Testimonies of the Women were of equal credit, i. e. of none at all.