I doubt if it's a coincidence. It probably influenced the choice of names in a version of the ballad that was influential. Just don't make any assumptions about "original location" or factuality of events.
As for class, it's difficult to know how the relationships have been used over the years. The action seems to be in a mediaeval setting (castles, hunting horns, swords), but the earliest extant versions are from the (English) Civil War period. My guess is that the ambiguity leaves scope for interpretations to suit the times, the singer and the audience, and that flexibility of appeal helped its survival.