Primarily Petroliana Shop Talk Forums Shop Talk Petroliana Forums Known & Suspected Unmarked Petro Reproductions How can you tell if a sinclair lens is original?

I'm looking to buy a sinclair Dino gasoline globe in the plastic capo frame. I just wanted to know how you can tell if the lenses are real or reproduction? I know some are marked repro but are they all? Also I've seen some with two copyright R's with the circle around The R. And I've seen some with only one copyright R. What's the difference? Also the version I'm looking at the DINO letters are in green.