Sei Lob und Ehr mit hohem Preis, BWV Anh. II 62b

The two choral preludes on the melody of "Sei Lob und Ehr und hohem Preis" BWV AnhII 62a and 62b appear in the same manuscript next to each other. I'm not sure why they have the numbers 62a and 62b instead of 62 and 63. They are of course related because they are based on the same choral melody. But the same goes for the three preludes on the melody of "Vom Himmel hoch da komm ich herr" and have each their own number.
BWV Anh. II 62b is a three part composition with the choral melody in the soprano voice. It has a certian playfulness and dance like elegance where the chorale melody itself, with its unexpected minor seventh does not sound playful at all to my ears.

Score available here: http://partitura.org/index.php/johann-sebastian-bach-sei-lob-und-ehr-mit-hohem-preis-bwv-anh-ii-62b