Assumptions

"Oh, a clone huh? And what made you come to that conclusion?" Song Zun's face had changed to show a weird emotion when Alex guessed that he was a clone. 

"You asked if I was a corpse that was strengthened and turned to a clone too, didn't you? That would mean that you were either one or were currently using one somewhere else. I would go as far as to guarantee that you are actually the one that is the clone"

"Which means… your real body is out there somewhere," Alex said with a stunning face. He hadn't realized what Song Zun being a clone meant before he spoke it out himself. 

"You… you have a real body somewhere else, and this is just a clone of yours that you made from a dead body. The clones are always supposed to be worse than the original. So, if … if the body that got to the 3rd spot in alchemy achievements and had immortal grade techniques is a clone then…"

Alex got serious and looked at him dead in the eyes and asked, "Who are you?"