Trenitalia have discovered forged tickets sold online and similar to some which have been found in Britain.

If you need to buy tickets in advance for train journeys within Italy I suggest you try the sales section of http://www.trenitalia.com .You can get this in English and it has an option to collect the tickets from machines at some big stations or from ticket offices. In some cases you can also print them off at home. Much easier than trying to explain to an Italian policeman who doesn't speak English.....