what are the motifs to why damtes chamges his name to monte cristo, sinbad the ailor, abbe bonucio

This certainly has to do with Dente's role as a God-figure who exacts justice on the wicked. Like some ancient Greek play, Dente's plays with the fortune and providence of different people by taking on a new persona. When Dentes feels like judging people, he's Abbé Busoni; He's Lord Wilmore when he feels like giving; and he's Monte Christo when he's dealing out some major payback!