I used to live at a twin address, my parents still do. It was across the boundary of towns and the homes are 500m apart. Postcode is only 1 letter different at

I used to live at a twin address, my parents still do. It was across the boundary of towns and the homes are 500m apart. Postcode is only 1 letter different at the end (e.g. AB1 1CD/AB1 1CE). The only issues I remember was getting each other's mail, and we'd just walk over and post it manually to them. We added a name to our property so we could use that in mailing addresses to help clarify.