Albert Barnes Commentary 1 Chronicles 24:20

"And of the rest of the sons of Levi: of the sons of Amram, Shubael; of the sons of Shubael, Jehdeiah." — 1 Chronicles 24:20 (ASV)

The purpose of this second enumeration of the Levitical families (compare 1 Chronicles 23:7–23) seems to be the designation of the heads of the families in David’s time. The omission of the Gershonites is curious and can only be accounted for by supposing that the author did not find any account of their heads in his source materials. The addition to the Merarites (1 Chronicles 24:26–27) is also curious. It brings the number of families up to twenty-five, which is one more than we would have expected.