  The magneto-transport properties of planar and layered strongly inhomogeneous
two-phase systems are investigated, using the explicit expressions for the
effective conductivities and resistivities obtained by the exact dual
transformation, connecting effective conductivities of in-plane isotropic
two-phase systems with and without magnetic field. These expressions allow to
describe the effective resistivity of various inhomogeneous media at arbitrary
concentrations $x$ and magnetic fields $H$. The corresponding plots of the
$x$-dependence of the Hall constant $R_H(x,H)$ and the magnetoresistance
$R(x,H)$ are constructed for various values of magnetic field at some values of
inhomogeneity parameters. These plots for strongly inhomogeneous systems at
high magnetic fields show a sharp transition between partial Hall resistivities
(or Hall conductivities) with different dependencies of $R_H$ on the phase
concentrations. It is shown that there is a strong correlation between large
linear magnetoresistance effect and this sharp Hall transition. Both these
effects are a consequence of the exact duality symmetry. A possible physical
explanation of these effects and their correlation is proposed.
