Is Xue king or not?

The so-called "king side by side" only exists in novels, but not in real history. Come to think of it, I died side by side with the emperor. Take the TV series "Xue" as an example, which boasted that Xue was named "King Side by Side". Looking up the official history of Tang Shu and Zi Tong Zhi Jian, we can see that the real Hou Xue curtain has never been sealed, and it has been returned to Wang ~ ~ Since the Western Han Dynasty, it has never been sealed with a different surname. There are only two possible ways to seal it: one is to pursue the seal after the death of a great hero, and the other is a necessary step before usurping the throne. The word "king side by side" is just a novelist's fantasy, which does not exist in history. So it can't be explained from a historical perspective.