This token is Franklin Mint DGT-58/H37. It appears to be brass, of which two were minted... the full Proof and the Prooflike. This token is in the proper plastic holder for a Presentation Proof token, but when out of the holder, it's not possible to tell the Proof from the Proof-like tokens that were in the collector sets from 1966. Since Dunes closed in 1989, it doesn't seem likely to me that the token was shipped by Franklin Mint 30 years after mintage.

I try to collect the presentation proofs in the octagon holders when the metal is different from the casino strikes and the collector set strikes; in this case, there's no way to tell, although a presentation strike was definitely made for this token. The holders snap together, and are not sealed. There were 500 made of the brass presentation strike and 3100 made of the proof-like brass in the collector set. There were also 500 silver-clad proofs of this 66 design made for the Full-proof collector set, and 6911 brass of the same design made for use in the casino.

Info is from the 1970 edition of the Numismatic Issues of the Franklin Mint .

From what I can learn, there was no difference in the striking prosess for the Proof tokens and the Proof-like tokens. All were from polished dies and the Proofs are the first off the presses. Franklin Mint had such high quality standards that all their tokens look great!