Dual bilinear rotations are introduced, which lead to well-defined rotations for both heteronuclear spins I and S that depend on the presence or absence of a (large) coupling between them. These are therefore an extension of conventional bilinear rotations, which cause such a spin-system-dependent rotation only for the spin I. A general derivation of the approach is given, and a quadruple-J-resolved type experiment is introduced for demonstration.