This piece on Inverse details some of the metaphysics and moral philosophy found within the Marvel Cinematic Universe, especially as explored in WandaVision's Vision.
Caution: Spoilers abound
Identity is a huge issue for superheroes. "Take away that suit of armor and what are you?" asks Cap to Tony, questioning his identity outside of his own creations. There's the issue of secret identities, like what Peter Parker deals with hiding his powers from his classmates. But for Vision in WandaVision, the question isn't "Who am I without my powers," but, "Who am I at all?"
Vision explains the paradox to White Vision through the Ship of Theseus, asking whether either of them are even Vision if they've both been replicated in ways that deprive them of personhood — if they even had that at all.
Dating back to Ancient Greece in the time of Plato, the Ship of Theseus problem supposes there was an ancient ship kept in the harbor as a museum piece. As its boards rot, they're replaced by new ones. After many years, every board is replaced. Is that ship still Theseus' ship? What if all the rotten boards were miraculously removed of their rot and reassembled? Would that ship also be Theseus' ship?
In this thought experiment, Vision is the replaced ship. While no part of him is the "original" Vision, he's the one who has replaced him both in Wanda's eyes and ours. White Vision is the reassembled ship, as he was miraculously repaired and brought "back," but is still missing a key part. There's no real correct answer. What makes a ship a ship? What makes a person a person?
Philosophically, the term "person" is hard to define in the MCU. After all, Thor isn't technically human, but he is in fact a person. If humanoid aliens can be called a person, why can't humanoid Synthezoids? And if Vision is considered a person even created through Wanda, then surely White Vision is too.
In fact, the scene with Vision and White Vision is philosophically interesting in a number of ways. In WandaVision Episode 8, Vision explains how he's always been alone. Now, he finally gets to be with someone who understands the sheer loneliness of being a synthezoid. So of course he's going to try to find a non-confrontational way of dealing with him — it's the first time he's been able to talk to someone who understands.
H/t Richard Kadrey
Image: Promo poster inset