A duplex is two homes sharing a wall. Normally look identical, but some times not. In other words its two apartments only. And our neighborhood uses house numbers instead of apartment.
So is this correct. I made two boxes, and made them houses with the middle wall going down the split. I can do this for my whole community if need be.
![alt text][1]
[1]: https://help.openstreetmap.org/upfiles/testhouse.pnghttps://help.openstreetmap.org/upfiles/testhouse.png
I Left one with out boxes so you could see the the style of building.