If you looking at the edges of the devices (either side of them) then you are looking at the areas affected by Machine Doubling. On the doubled dies, the center part of the devices will be enlarged. (I am aware that my images are from a different mint, but using them for the purpose of what hub doubling and machine double shows)
So on the doubled dies, the doubling is on the die. Each strike will show the same spread.
On Machine Doubling there is no rules. Each strike can be different because the MD happens after the strike with a loose machine altering the device. These are caused by the machine. Doubled dies can also be affected with Machine Doubling also.