It's just a historical mistake. (and according to me there's no real valid reason to name JavaScript as JavaScript)
They have similar names because market was crazy about these new technologies when they were starting to come out (actually Netscape was about to include Java inside Netscape) and they accidentally chose to change LiveScript name to JavaScript. I wrote accidentally because they have nothing in common (apart from being two programming languages) so there's no a real, analytic reason for this similarity.