Textures loaded from Material on Material Instances sons too?

I’ve noticed from Statistics-> Textures Stats that I’ve some textures loaded in my level that should not be there.
Further investigation made me discover that those textures were loaded cause they were default textures in Parent Master Material of my Material Instances.

Let me explain better: I have a Master Material with 3 2k textures: let’s call it MASTER and its Textures MASTER_A. MASTER_N and MASTER_ORM.
I’ve created a Material Instance from that, where I’ve substituted all default MASTER textures with different ones.
So I’ve INSTANCE with INSTANCE_A, INSTANCE_N and INSTANCE_ORM.
In my level I’ve applied only INSTANCE material and in Textures Stats I can see that the engine has loaded INSTANCE and MASTER textures too. So I’ve 3 2k textures unused that are always loaded in memory, no matter what.

It’s a version problem, it will always be like that or I’m missing something?
This could lead to big memory problems in particular cases…