Edward F. Campbell Jr has a possible explanation in his essay, 'A Land Divided: Judah and Israel from the Death of Solomon to the Fall of Samaria' published in The Oxford History of the Biblical World. He says that problems arise with the kings who succeeded Ahab in Israel and Jehoshaphat in Judah. In Israel, Ahab's successors were his sons Ahaziah, who ruled for parts of two years, and Jehoram, who ruled for roughly seven years (although the Deuteronomist gives him twelve). In Judah, Jehoram, son of Jehoshaphat reigned for seven-plus years and Jehoram's son Ahaziah for less than a year.
Notice first that the period is approximately eight years in both cases. Any error, intentional or otherwise, would not affect the list of kings in either kingdom. Then, Campbell says the duplication of the name Jehoram, even if in reverse order, is startling and has led to speculation that the kingdoms were really under one rule. It seems very likely that Judah was conquered and occupied by Israel during this period, but the national pride of the Judahites required them to cover this up (remembering that the Bible is the only written record we have, and this comes to us from Judahite sources). On the view that there was actually no Judahite king, the sources changed just enough details of the kings who were their real rulers (the Israelite kings) to disguise the facts - reversing their order and changing the periods of their reigns. Anyone else in Judah at the time of writing, who had independent testimony of two kings called Ahaziah and Jehoram who happened to rule Judah, would simply assume that they were the two fictional kings of Judah and not their Israelite overlords.
If this explanation is eventually proven to the satisfaction of all critical scholars, then we can say there was no precedence of one Jehoram over the other, as there was only one Jehoram.