The Notorious B.I.G. first went by Biggie Smalls. Jazzy turned into Jay-Z, which then turned into Jay Z. Nas stepped up his hygiene regime and dropped Nasty.
As artists evolve and mature professionally and personally, their aliases sometimes become a symbol of that change. Or sometimes someone has the same or a similar name, as was the case with 23-year-old Palm Beach rapper Croosh.