It's because all the princess' are the same. They were all "Princess Peach" in japan. But like almost all japanese stuff that comes to america (edited DBZ, Games, you name it!) things got changed. And we couldn't decide on a name. That is why there are so many different princess'. There is only one in japan, and I wonder how they got Princess daisy in Mario Tennis. Just somthing to think about, how well do you know Mario?
Doomba, King of the Goombas