This is me holding a book written by a Chen's group in New Zealand. I had to borrow this. China is very big with over 1.4 billion people and people speaking different dialects. The writing however is the same. I grew up where there are different dialects, and my Quang Ning Chen is written as Chan. There are others, Ting/Ding Foochow, Tan Hokkien Chin Hakka.
To make it more complicated, I married a Hakka whose Chen is Chin, hence my professional name is Chin-Chan.