Why do some sims have a "twin"?

Why do a few sims seem to be coppies of each other? Take DeHaro and Green, for example. They are geographically identical (if you exclude player terraforming)- both have the scame cross-shaped lake. Why is this? Is it a memory saving trick where the same Linden-owned land can be generated once and displayed in two places?
Just curious.

DeHaro and Green were both of the same purpose, long long ago. The 'newbie campgrounds' similar to Boardman and Brown, but with the restriction of using a tent or cabin rather than just being 'residental'. They probably look the same since someone got lazy. :)

My guess is that LL initially planned to copy this pattern all over the grid, but they quickly found out the amount of support needed to manage these zoned communities didnt scale, so they stopped after the second continent.