after checking again and playing around with it , it is no longer creating the texture files
and i do not know why or how it created in the first place
bit of a pity it helped my debugging
not sure whether a render target will keep a cache or something on disk
or whether a material that is fed a render target will keep a cache
or applying a material to an object will spawn a texture in file
only thing i can think of why the textures were created