Environmental effect, damage. 70 years since they were minted.. this is one of the things that just occurs.
Purple, Probably environmental issue. The second coin (1951D) is damage. Look at the area and you can see metal that is pushed up along the edges.
Copper can turn purple when exposed to the right chemicals and/or conditions. Nice but environmental problems.
Look like dug pieces to me and I've seen quite a few over the years. Chemical staining in any event....
