Problem: Here we are informed that Josiah destroyed the altars and idols, but earlier (in 2 Chron. 33:15) Manasseh had destroyed them.
Solution: No human king can root out the depraved human desire for idolatry. Therefore, Josiah had to redo the same work that his predecessor had done. A good human king can destroy idols, but not the love of idols. And, as long as this love exists, idolatry will live to rear its ugly head again and again.