Question About Types Of Doubling

The primary difference is how the doubling is created. On a doubled die the doubling is hubbed into the die. Differences in the hub/or application makes the die doubled. Every coin struck from that die will be doubled exactly the same. On a machined doubled coin, the die is normal, but be cause of looseness/play in the mechanism, the image get distorted on the devices of a coin. From coin to coin they may be different some normal/some minor/some major or anything in between. If the operator notices this and adjust the machine, the coins will be normal again till the machine needs adjusting again. The doubled dies are collectible as they can be listed as being from a certain die. They are called varieties. Machine doubled happen commonly and don't warrant any extra premium as they are teasers sold to newbies and they get burned on them. Something honest hearted collectors do not what to happen. Education first, purchase second.
Here is an example of machine doulbled and doubled die coins. See if this helps.

Note on the machine doubled examples the metal is distorted. On the doubled die images the devices are wider/taller because of the hubbing having a spread present.

Your coin appears to be called a strike through error. It appears that grease fille some of the devices on the die, preventing the design to be formed during the strike.
Don't forget to click on the images if they can be made larger.
https://www.coincommunity.com/forum...eddie_01.jpg
https://www.coincommunity.com/forum...e_filled.jpg
https://www.coincommunity.com/forum..._Dies_01.jpg
https://www.coincommunity.com/forum...D_DIE_01.jpg
Extra Value would be for very strong examples. Just a small amount, more of a collectors item for educational uses.
https://www.coincommunity.com/forum...th_sides.jpg

thanks coop,lots of help,now I understand

nice write up coop