Some textures on my terrain are way too bright

i have 2 textures on my terrain with normal maps , i applied a shiny material to the terrain everything done properly but when i paint my textures on my terrain one texture is way brighter than the other . i don't think that matters but the size of the non too bright texture is 512x512 and the too bright one 1024x1024. what did i do wrong ?][1]