Albert Barnes Commentary 2 Chronicles 28:5

"Wherefore Jehovah his God delivered him into the hand of the king of Syria; and they smote him, and carried away of his a great multitude of captives, and brought them to Damascus. And he was also delivered into the hand of the king of Israel, who smote him with a great slaughter." — 2 Chronicles 28:5 (ASV)

The two battles mentioned here, one with Rezin (king of Syria) and the other with Pekah (king of Israel), are additions to the narrative of the writer of Kings. The events of the Syro-Israelite war were probably spread over several years.