I thing this coin it is a Mint error, which include planchet error. One side is concave with no letters damage, and the other side have an small inner punch circle done before the die strike with no doubt of.
Do have 2.07 gr and 18.03 mm in diameter and 1.16 mm thickness? Intrigue me the fact the dots rim are far from the edge, also the ridded of the coin (not see very well) has bigger distance.
By the design I will estimate 1979 to 1989 the year. Here attached the photos together for better look.