They are indeed the same.

The tune name, "Our Gude Man," however, probably means no more than that it is a version of that song.

I have no idea where The Four Sergeants came up with their "double" tune. It may have been suggested by the recording. There is no reason to assume that it was "field-collected" with Shay's lyrics, but we simply don't know.

Somebody had to combine the two at some point.

But it's probably safe to say it was sung "in tradition" by very few people - if that many. (I performed it in class a few times with slightly saltier words from other versions, but I'd be amazed to think that anyone could have learned it from me, much less passed it on.)