Just like moved snow, the metal can be moved and pushed in a new location. That is not spread, but
Machine Doubling. The pushed area is where the snow was moved, and now piled up higher. (moved, not raised like a doubled die)

Note on this cent, how the metal was pushed aside. Not a doubled die. Looking at the edges of the devices Inside or outside of the devices, will show you
Machine Doubling and die wear. Look at the centers of the devices in order to find hub doubling, enlarging the size of the devices on the centers. (not on the outer/inner devices)

Note this side by side. Top is normal, the bottom is a
DDR. Note the spread on the centers of the devices, the enlarging the devices and the corner notching? Look at the centers of the devices, that is where you will see the spread of a doubled die.
CoopHome:
Why can't I find a doubled die and I am distracted by Machine Doubling? Look at the centers of the devices and not on the edges of devices.