Because it's a conspiracy. Katy Perry is actually pretending to be Katy Hudson but she killed her and took her place. Now she says she record Katy Hudson but we all know it's all LIES
It's like saying Selena's debut album is Stars Dance, because all her other albums were released under the name Selena Gomez & the Scene.
Selena Gomez's debut album is Stars Dance, whereas Selena Gomez & The Scene's debut album was Kiss & Tell. They're 2 different acts. Get it now? It's like saying Destiny's Child is Beyonce's debut album.