Lithuanian-American science fiction author Algis Budrys emphasized the question of identity, featured in his three major works: Who?, Rogue Moon, and Michaelmas.
Read this. What this summary doesn’t explicitly state about Rogue Moon is that the “matter-transmitter” makes the copies by scanning the person’s original body and coding the information – a process that completely destroys the original body (the copies are reconstituted from any available matter). Thus, there is a question of identity: Hawks insists that the copies are NOT the original, despite being biological duplicates and sharing the memories of the original. And when Barker and Hawks (copies of the originals) both travel to the moon (via the “matter-transmitter”) and survive the artifact, Hawks insists that they can never go back to Earth, because their duplicates (also copies of the originals) are already there, living their own lives. This moon version of Hawks kills himself after stating this, by walking away and letting his air run out; the Earth version of Hawks continues his life (although he is a copy of the original Hawks, and bitterly cognizant of that fact; the Earth copy of Barker, by contrast, could care less). For a somewhat similar theme, see this Outer Limits episode.
The question of identity in Who? Is obvious and at one point, when nothing is left to be done, Rogers asks the man in question point-blank: “Martino, are you Martino?” The answer he gets back is a simple “no” – even though (spoiler alert!) we find out at the end that it really is Martino. After everything that has happened to him, his sense of self, his identity, has been erased.
In Michaelmas – which unfortunately contains snide attacks against “xenophobic populism” – the question of identity is also considered, as it involves copying individuals as well.
Issues of identity are of course of interest to us, so these works may be useful reading. Indeed, regardless of Budrys’ politics, his work clearly suggests that identity – sense of self – depends upon the authenticity and integrity of physical being. That is certainly compatible with a racialist worldview; hence, these works are of value from that perspective.