Eadem_Natura__Duo_Spectra

This paper establishes Eadem natura, duo spectra: a single underlying admissible structure admits multiple representational spectra without introducing distinct ontic domains. It shows that apparent dualities arise from standing-preserving redescription rather than from independent foundational layers. By exhaustion, all interpretations that treat the spectra as separate realities, complementary ontologies, or reducible via translation rules are eliminated. The result fixes duality as a representational phenomenon constrained by admissibility and standing, not a generative or explanatory mechanism. No algorithms, constructions, or procedural mappings are provided; the argument is necessity-based and post-exhaustive.