From your scan, it looks like the token was struck from the normal 1980 die. Sometimes tokens are discolored do to methods of storage or from being purposely doctored. It could also be an off-strike. Many casinos have had off-strikes produced for high-rollers, management, etc. Its hard to tell from the scan but it looks like the coloring is uneven, especially at the rims - could mean that the base metal is the original nickel.