  Markushevich and Tikhomirov provided a construction of an irreducible
symplectic V-manifold of dimension 4, the relative compactified Prym variety of
a family of curves with involution, which is a Lagrangian fibration with
polarization of type (1,2). We give a characterization of the dual Lagrangian
fibration. We also identify the moduli space of Lagrangian fibrations of this
type and show that the duality defines a rational involution on it.
