Contradiction with 2 Kings 18:3
Unlike 2 Kings 21:21, where Amon walked in the way of his father Manasseh's evil practices, this verse describes how Hezekiah did what was right in the sight of the Lord, following the ways of David.
2 Kings 18:3: And he did [that which was] right in the sight of the LORD, according to all that David his father did.
Contradiction with 2 Chronicles 33:15
Contradicts 2 Kings 21:21 by showing Manasseh's later repentance and removal of idols, whereas Amon continued in those practices.
2 Chronicles 33:15: And he took away the strange gods, and the idol out of the house of the LORD, and all the altars that he had built in the mount of the house of the LORD, and in Jerusalem, and cast [them] out of the city.