JoramJoram - The two kingdoms both had kings named "Jehoram" whose reigns overlapped for a period of time.  In order to distinguish them from each other, one is often referred to as "Joram".

 

"Now Jehoram the son of Ahab became king over Israel at Samaria in the eighteenth year of Jehoshaphat king of Judah, and reigned twelve years.  He did evil in the sight of the Lord, though not like his father and his mother; for he put away the sacred pillar of Baal which his father had made.  Nevertheless, he clung to the sins of Jeroboam the son of Nebat, which he made Israel sin; he did not depart from them." (II Kings 3:1-3, NASB)