First building appears as following:
Building 24, Kiril i Metodij, Македонски Брод, Makedonski Brod, Municipality of Makedonski Brod, Southwestern Region, 6530, Macedonia
Second building appears as following:
Building 24, Braka Miladinovci, Македонски Брод, Trebino, Municipality of Makedonski Brod, Southwestern Region, 6530, Macedonia
Trebino is a Village a bit on north of Makedonski Brod, why does the second house being in Makedonski Brod appears as from Trebino ?
Trebino is mapped as a point http://www.openstreetmap.org/node/391880967 As such, the only way that the reverse geocoder (Nominatim?) can decide whether or not something is in it is by distance. One house is probably marginally closer.
If you want accurate reverse geocodes for the administrative hierarchy for a location, you need to map the boundaries as areas. However, that depends on having a source that you can legally use to do that. You may find that some places don’t actually exist officially, so their boundaries are not well defined.
I’m not sure what the policy is on doing a best guess for boundaries, based on boundaries signs on roads, etc., but even if that is considered OK, there may well be houses that are one side of the official boundary, but the other side of the best guess based on usable sources. The policies may vary with country and administrative level.
Incidentally, Trebino claims to be in Porece, but Porece isn’t on the map! That can’t be helping.
Generally, you should not expect reverse geocodes from Nominatim to match what the locals would expect, and you certainly can’t expect them to give postal addresses.