It does make sense that exits have their appropriate number ref tag, but I think that only one of them should be rendered. Having two of the same numbers close to each other on the same highway is not very clean. See what I mean: https://imgur.com/a/yL4JroP
As you can see, exit numbers 18A, 12A, 11, and 10 are rendered twice on the map (which again, makes sense due to them being labeled in both directions).
While the ref tags should be kept on both nodes of each pair, I think only one should be rendered. Does anybody agree with this?