We all know that Qin Shihuang's name is "Ying Zheng", but why do people sometimes say that he is also called "Qin Zheng", "Zhao Zheng" or even "Lu Zheng"? In fact, we can get clues for this reason from Sima Qian's "Historical Records".
In "Historical Records: The Chronicles of Qin Shihuang", there is a saying that "Ying's surname is Zhao", and this statement is also the origin of "Qin and Zhao share the same clan". This sentence means that if Ying Zheng's surname can be traced back, it can actually be traced back to the same clan as Zhao.
Because the ancestors of Qin and Zhao were from the same clan, later, after the Zhao branch developed first, the descendants of this branch simply followed the Zhao surname and called themselves the Zhao family.
With the rise of Qin, the other branch, like the Zhao family, took the surname of Qin and called itself the Qin family. It is worth noting that in the pre-Qin period, men were called family names instead of surnames. In other words, the descendants of the Zhao family and the Qin family both had the original surname Ying, but they all called themselves Zhao or Qin. It is for this reason that it is not wrong for Qin Shihuang to call him "Zhao Zheng" or "Qin Zheng".
After Qin Shihuang ascended the throne and became the first emperor, because the surnames of Qin and Han merged, Qin Shihuang returned to the surname. Therefore, we basically call Qin Shihuang "Ying Zheng", which is very convenient. It is rarely called "Zhao Zheng" or "Qin Zheng".
As for some people saying that Qin Shihuang also had the name "Lu Zheng", this is probably spread from folk history. Because there are rumors among the people that Qin Shihuang was Lu Buwei's illegitimate son, his real surname should be Lu. Therefore he should be called "Lu Zheng". However, because this statement is unreliable, basically no one adopts it.