How come misono and Koda Kumi have different last names?

[Findlay]

Originally Posted by leafyamazaki

Like what matt said.

Anywho, on one of the japanese fansites:
神田美苑(こうだみその ) <-- Kouda Misono / Koda Misono
[from dear another triangle]

Oops I forgot 神田 can also be pronounced as Kouda, cuz in most common occasion we say it Kanda. Still, why did they two choose to write it in different ways in terms of kanji? o_O