Apparently It's A Tradition Within The New York Legal System.

https://english.news.cn/northamerica/20240531/5d70c5f8b4b547b0a2e4f485bcf54417/c.html

Upon taking up a Judgeship you have to assume the name; "Juan Merchan."

It helps with security. Giving the impression it's the same Judge acting in every case. 

We'll just have to trust that his daughter ensures the expense is properly recorded in the Democrats next campaign finace declaration.

https://news.sky.com/story/new-york-could-scrap-law-that-criminalises-adultery-13099641