I sadly know nothing about Mardi Gras Doubloons, Michael Drago who supplied these coins, wrote

"Mardi Gras Doubloons are brightly colored aluminum coins about 40mm in diameter. They are thrown by Krewe members from Mardi Gras floats. Doubloons usually have the symbol of the Krewe on the front along with the date the Krewe was organized, the back side usually has the theme for that years parade as well as the date. Each Krewe may have a number of different doubloons for each years parade. Usually the silver ones are the most common, followed by a range of colors from red to gold.

They are a another fascinating addition to Arthurian collectibles.