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 62a employs the same technique as BWV Anh. II 61. The choral melody is played as bass voice, and the two voices played by the hands provide a lively accompaniment. Bach as a composer is not impossible, but also not very likely. It feels more like a composition by Johann Pachelbel than a composition by Bach. Nevertheless, it's a nice piece to play.