1964-D Dime OBV Device Die Clash?

As I do on most Fridays, I stopped at the LCS to look at his 90%. A great place with a very nice couple that owns it, they have no problem with me sorting through their buckets at my leisure. I pick out some very nice coins.

As I am cataloging the coins I find a 64d with something on the bridge of his nose, then another, and finally one more.







Upon closer inspection I find this. All 3 identical to the severe polishing marks and a die crack that runs across M in dime on the back.

I almost feel like I'm vamming but anyways.

1st, This would be a die clash?
2nd, The severe polishing on the obv would indicate a recent clash, but obviously some of the clash wasn't removed?
3rd, Any reference material, websites that track these clashes?
4th, This chinchilla just had to be in this thread.