A while back, in a discussion about the She'ar Yashuv minhag for badekin music, I wrote:
The other tune they sing, Keili Ato, is a Chabad melody. I've heard that the melody has evolved/simplified over the years, but the recordings and notation I've seen of it all have the melody as it is commonly sung today. If anyone has info on this, please forward it this way.In response to that post, a couple of readers sent me lead sheets, but they were all identical.
Today, I took a look at the melody as notated in the Sefer Hanigunim, and noticed that it is, in fact, slightly different than the popular version.
These subtle differences include the lack of repeats, the melody in bars 2-3, and the rhythm in bar 3. It seems as though the melody has evolved to people singing a few notes of harmony instead of the original melody.
I've noticed several popular melodies that have evolved in similar manner. One example would be Eitz Chayim (on the last phrase of the A section).