separate sidewalk on one side, shared with road on the other?

Some sidewalks that are separated from the road by verge have been added near me. In some places there are streets which have sidewalks on both sides but only one side is separated from the road and only that side has been mapped as a separate way. Is that okay? How should the road be tagged in that case? Just sidewalk=left/right for the adjoined sidewalk, or any way of mentioning the separate sidewalk too (would usually be sidewalk=separate)? Or is sidewalk=separate useless (is it used by any data consumers)?