Presidential Dollar Edge Letter Errors

Those are really cool.

There is no incusing process. The edge die presses it into the edge during striking.

I know the lettering was added to the coins in a seperate step from
striking, for business strikes.

I am not sure of the exact process, I can imagine the planchets or coins
were dumped into a hopper and fed into a machine to add the edge lettering.
I am not sure if it was done before or after striking, my guess is before
striking. The first year some missed the lettering process and some were
put through twice.

There is a web site that has some good information on these, I will
have to find the link. I have read there are estimated 8,000 to 12,000
of the double lettered coins.

There is a proof error, it has the lettering out of sequence.

There is also one business strike with the wrong date. I think one of
the 2009 coins with a 2010 date.

Edit - CK ....yes the inverted (slabbed) one has one set of edge letter
right side up (position A) and a set of edge letter upside down (position B)
The coin that was in the 2X2, has both edge letter strikes in position B.