The two DT texts name no proper sources (the Clancy Brothers could have got the song from Peruvians, for all the information we're given, and the other file acknowledges no source of any kind); so they are worthless to anybody wanting to know about the song's background.
At a rough guess I'd think that the second DT file is a transcription from a record made by revival performers; a slightly garbled take on the O Lochlainn set.
Probably the first file (as recorded by the Clancys) was also got from O Lochlainn's book. The chorus is almost certainly a bogus Clancy invention aimed at lowest-common-denominator "singalong" audiences. A speciality of theirs.
For what it's worth, Lochlainn himself provides no useful source information.