Integrable deformations of the hyperbolic and trigonometric BC n Sutherland models were recently derived via Hamiltonian reduction of certain free systems on the Heisenberg doubles of SU(n, n) and SU(2n), respectively. As a step towards constructing action-angle variables for these models, we here apply the same reduction to a different free system on the double of SU(2n) and thereby obtain a novel integrable many-body model of Ruijsenaars-Schneider-van Diejen type that is in action-angle duality with the respective deformed Sutherland model.