I've seen all manner of 'sample' and 'display' plates, stamped-out + issued over the years by just about any jurisdiction with the authority to turn them out. After all --- world's full o' tourists. With money. These plates usually get identified as such, maybe carry a funky number sequence --- something obvious.
The Real Deal usually looks like, well --- a bunged-up old plate . . . nothing too too shiny/pretty.
Also helps to have some references handy. . . .
http://www.worldlicenseplates.com/jp...1970's.jpg
;)
Rick