When a geometric modification of spacetime is equivalent, by a field redefinition, to a theory we already know, does anything physical survive the equivalence? We examine a metric-compatible contortion of the form $K^lambda_{ muu} = F(phi),epsilon^{lambdaho}_{ muu},partial_hophi$, generated by the gradient of a scalar field and totally antisymmetric in its three indices, which is unique within its class once one requires that spinless particles follow the geodesics of general relativity. The Ricci scalar acquires a correction $R(Gamma) = R({}) + 6F^2(partialphi)^2$ that shifts the scalar kinetic term by a factor $1 - 6F^2/kappa_g$, yielding a ghost bound $M_F > 0.49,M_{m Pl}$, and the Schwarzschild metric remains an exact vacuum solution when the scalar field is constant. We show that the bosonic sector is equivalent, by a field redefinition, to a canonical scalar field minimally coupled to general relativity, so that the modification of the Kalb-Ramond duality is a statement about the parametrization rather than about the physical spectrum. The survival of a residual coupling in the matter sector is not specific to this construction, since it also occurs in the Jordan-Einstein frame equivalence of scalar-tensor theories, but the form of the surviving coupling is. Here the residual coupling is parity-odd, spin-dependent, and non-universal, affecting only matter with spin. We estimate the magnitude of this force in a cosmological background and find it to be far below observational sensitivity; we do not claim that it becomes observable in regimes that we have not calculated.