Chrono Cross had this tendency to change practically every character's name when it was translated from Japanese into English. Some were changed due to length restrictions, some I have no idea why they changed, and then there's Nikki - he was supposed to be called Slash, but his name was changed for completely different reasons.
If you're lucky enough to have played Chrono Trigger, one of the villains in the English version was named Slash. If you beat Chrono Cross and start a new game plus (or continue plus) you can go the bends of time and enter the door which you couldn't previously and fight Slash, along with Ozzie and Flea! This was one of my favourite side-quests because hello - Flea! <3
But I digress. In the Japanese version of Chrono Trigger Slash was not called Slash, he was Soy Sauce. So in Chrono Cross he was also Soy Sauce and Slash (Nikki) could be Slash. In the English version, however, you can't have two characters with the same name, so Slash (Nikki) had to be changed to Nikki.
(True Facts: I actually prefer the name Slash, but this site is based on the english version of Chrono Cross so I call him Nikki for reasons of accuracy.)