coupled together from bottom to top and fitted into a single ring. He made both corners in this way.

And they were double beneath; and in like manner they were entire unto the top thereof unto one ring: thus he did to both of them in the two corners.

and they have been twins below, and together they are twins at its head, at the one ring; so he hath done to both of them at the two corners;

and they were joined beneath, and were coupled together at the top thereof into one ring: thus he did to both of them in both the corners;