Hello everybody. I'm new to these forums / coin collecting and am curious about this 1972 Canadian dime that I came across. Here are photos of both the obverse and the reverse.
http://imgur.com/a/8GouaAs you can see, there appears to be two rings stamped into the center of the obverse of the coin, and no damage whatsoever to the reverse of the coin. What could have caused this? Is it a mint error or did something else cause this?