Steps to repro:

1. Launch Unity
2. Create a new Material
3. Assign any texture to Albedo
4. Assign a texture to Normal Map (The texture must NOT be set to 'Normal Map')
5. Duplicate Material node with Ctrl+D
6. Hit 'Fix now' on the duplicated node.
7. Observe in the inspector; node doesn't update.

There is a slight improvement from 5.1x where the material would not update at all, regardless of being duplicated.