Jiang Fengxian's situation is just like that; there's nothing that needs to be concealed.
Although the man in the black robe is a clone of some "Celestial Immortal," he cannot possibly know everything about the "Spirit Realm," including the existence of the "Celestial Phoenix Race," which he is unaware of.
A brief explanation here is needed: the clones cultivated by High-Tier Cultivators generally fall into two categories.
One type is purely used to enhance combat and survival skills; these clones lack independent consciousness and can be seen as special Magical Artifacts, their actions entirely directed by the consciousness of the main body.
In other words, this kind of clone is equivalent to a death warrior that obeys the main body unconditionally, serving primarily to brave dangers.
