When I had access to the electoral rolls on Ancestry I found that my maternal grandparents were living next door to my grandfather's brother, and that they were still neighbours the following year. However, in the later roll my grandparents were also listed as living at a completely different address. Does this mean they moved after registering, and were registered again at their new address?
Quite possibly. This has happened recently to the previous owners of my house: they were registered at their new place in Yorkshire whilst also here in Northamptonshire. It was apparently my responsibility to let the authorities know that they were no longer living here - which I did, but the wheels of the registration authorities were rather slow....