Artifactes when texture painting beetween two objects

Hi ! I need some help about Blender texture painting. I’m trying to do bump mapping on environments, so i use texture painting with normal map directly on the model windows. With the same preset on my brush (a line) for two differents objects, i get a different result on the borders of the line, plus we can see artifactes between 2 objects… Do you know how i can fix this ?