He built a railroad 
More seriously, when you said "after claiming a couple cities" do you mean that you conquered one or both of the ones that later built the double road?
But I think it's just that you have a road going from Aweyoli to Tisunisu and a road going from Voxif to Tisunisu and they run in parallel (the map squares apparently only track the fact that they have road on them, no directional info, so graphically all road connects to all adjacent road regardless of the main direction it conceptually was laid in).
And the leftover unit statue from a killed sov is a known bug, but thanks for mentioning it.