Goddamn it man, cloud was out of his head by the time Zack died. The way the story goes is that Zack busts out of the testing chambers and frees cloud, then zack puts on a uniform on cloud and carries him away. The reason cloud stole zacks identity was because he didnt know any better, the jenova cells in his blood screwed up his brain and he actually belived that he was zack. He did steal his sword tho! lol