Have you seen it before where army or police stamp their own VIN?
No idea what happens in Italy, but police or registration authorities sometimes re-stamp numbers where something weird has happened to a machine, say it has been stolen or the original number disfigured. In Victoria, Australia, for example, the Victorian Police use numbers VxxxxxxxxP (where the xxx are numbers).
Just recently we discussed a 1929 Coventry Eagle in Spain that had a quite elaborate engine number stamped on it, in addition to its original JAP engine number that was still in place.
Strange things happen!
Leon