Found a 1976 Roosevelt dime with a filled "D" mint.

[mr helton]

Any idea how common this is?

 

[cudamark]

Very, especially with worn out dies.

 

[50cent]

Any coin from the 70s can have this..... Quarters come to mind....(have not really seen halves) SBA has the filled letter syndrome, saw some dimes, even a nickel. it be worth clad lad