Adam Clarke on Jeremiah 33:24

The two families which the Lord hath chosen - Some think these refer to the two kingdoms of Israel and Judah; but they never can be considered as two distinct families, being of one and the same race. Others think that the families of Jacob and David are intended; but neither were these distinct. If the two families which had the priesthood be not meant, then the regal family of David, and the sacerdotal family of Jacob through Levi, may be designed. See Jer 33:26. Following the spiritual interpretation, neither the regal nor sacerdotal family has failed; for Jesus is a King and a Priest, and all true believers in him are kings and priests unto God and the Lamb. And the highest King that ever reigned is He who is the seed of David, King of kings and Lord of lords, who has all power in heaven and in earth.