@HarryHawk It wasn't unknown for two versions of a song to be hits around the same time. I remember two versions of "Amazing Grace", an instumental version by the Royal Scots Dragoon Guards (played on bagpipes) and a vocal version by Judy Collins.
@MissBarbara I remember those too. I think there were also two versions of 'Blame it on the Boogie', one by the Jacksons and the other by the chap who wrote it, Mick Jackson (no relation)