  Transversity generalized parton distributions (GPDs) can be probed in
diffractive electro- and photoproduction of two vector mesons on a hadron in
kinematics where the two vector mesons are separated by a large rapidity gap.
We report on calculations for this process in the case of coherent
$\rho^0-\omega$ meson production on a deuteron target. Our cross section
results show that an electron-ion collider with deuteron beams and forward
detectors could probe deuteron transversity GPDs.
