Albert Barnes Commentary 1 Chronicles 9:19

"And Shallum the son of Kore, the son of Ebiasaph, the son of Korah, and his brethren, of his father`s house, the Korahites, were over the work of the service, keepers of the thresholds of the tent: and their fathers had been over the camp of Jehovah, keepers of the entry." — 1 Chronicles 9:19 (ASV)

Shallum the son of Kore - A different person from the Shallum of 1 Chronicles 9:17, with a different office: namely, guarding the inner doors of the temple. The original Shallum, Shelemaiah, or Meshelemaiah, was a Levite from the time of David (1 Chronicles 26:14). His descendants were still called by his name but were now assigned a more important charge.