If one alters a public domain work, let's say restore it or add different music, the altered work is NOT in the public domain. Take for instance Death Rides a Horse, of which there is a terrible looking public domain version. It can be found here http://www.publicdomaintorrents.com/nshowmovie.html?movieid=788 The restored version however, is not public domain. And that wouldn't be right either, as you say. But, since the market is flooded with crappy releases, it's not commercially attractive to restore these old movies. That's why you get all these crappy Boot Hill-like releases. Maybe we should all chip in and form a consortium to restore some spaghetti westerns, hehe. My first choice would be Fidani's Savage Guns. I'd love to see a good looking version of that movie.
On topic: My DFW dvd of Today it's me, tomorrow it's you is licensed from Atlántida Films S.A. So I reckon they own it.