1967 50c Unlisted DDR & DDR Die Pair. (Pic Dump)

What do you mean by DDR-DDR die pair?

where do you see the doubling on reverse? not sure if the obverse doubling is a true hub doubling or the working hub!

now that you mentioned I can make out the notches on the Stars below the D and S (mostly occur in that area)hard to distinguish due to the toning.
In this case you may want to correct the title to DDO & DDR

that could well be an unlisted one since there are so many still being found, but I am not certain..

@E&V how does that process work?

I'm not seeing much in the way of doubling. The 'T' on LIBERTY is coin contact. Even with two devices in an image on the date area. I'm not seeing anything of note. The doubling must be a lot stronger to see for a true collector of doubled dies would show interest. Keep in mind that if they can't see it with a 10X loupe, they are not interested. Keep in mind in order to see what is really there, you need 3 large device per image and 4-5 smaller devices per image. That will show us how strong something is. Scanning into a single device gives us no point of reference of how strong the spread is. Also consistency of spread. We need to see it that it is just not one device that is affected. Hub doubling means that the hub is doubling the die and this should be seen on other areas of the coin.

Note the spread enlarges the devices. The spread is noticed on the center of the devices. Not just the edges of devices.

Again note the spread of the devices. There is notching on the corners of some devices. But the spread from the hub on the die enlarges the devices.

Again note the spread. You look at the center of the devices. You see the devices are enlarged and there is notching on the corners, not on the sides. Machine Doubling affects the sides of the devices.

Again, looking at the centers of the devices we see that the spread or enlarging of the devices are present. Notching is on the corners of devices.

More on the way