Hi theremte
Thank you for posting this.
According to your image, you're providing only 7 different textures to feed up the material; am I correct?
As @pokoy already mentioned, at some point, the same textures will appear again as the shader places each one of the provided textures; it will run out of textures and will start over, placing them in a different location.
If you need a more solid randomization, I'll suggest using more textures to feed up the shader/material.
I hope this helps.
If this is not what you were trying to communicate, please let us know.
Have an amazing weekend ahead.