Does anyone know anything about this Italian film?

Leonard Maltin lists a film in his Classic Movie Guide for which I cannot find any other information.  Does anyone know of it and can add it to IMDb?

Prisoner of the Iron Mask, The (1962-Italian. C-80m. D: Francesco De Foo.  Michael Lemoine, Wandisa Guida, Andrea Bosic, Jany Clair, Giovanni Materassi. Usual costume shenanigans: an evil count impersonates a man who has proof of the nobleman’s treachery. Based not on the expected Dumas novel, but on his Ten Years After.  D’Artangan and The Three Musketeers do not appear. Techniscope.

The Dumas novel is usually listed as: The Vicomte of Bragelonne: Ten Years Later