Overexamining things is one way of acquiring knowledge! One man's meat!

Brian. Here's one for you. In the late 60s, early 70s Jim Eldon and I found a veritable nest of singers in a small village on the East Riding coast. One of the interesting things was that different singers could sing us vastly different versions of the same songs and this was from singers living practically next door to each other for most of their lives. An interesting example arose that seems to suit your criterion. We had 3 different versions of 'An Acre of Land' (an offshoot of Child 2), that is, different tunes, different choruses and different run-downs of items in the crop growing/production cycle. After a few weeks 2 of the singers who had sizable repertoires were getting on famously, not having been aware of each other's singing previously. Of course we went back to record the female singer a week or so later and found she had extra verses in her version which she later admitted she had nicked off her male neighbour. All 3 versions can be heard on the Yorkshire Garland website, but the quality of recording is rather poor due to our cheap original equipment.