Thanks for the clarification, sorry for the misunderstanding.

What should be happening is that ArtRage writes a .nomedia file to the internal storage> artrage> preview> small folder but that doesn't appear to be happening, so we'll look into that for the next update. That should prevent the small images from showing in the Android gallery.

In the meantime, if you drop a blank file into that folder named .nomedia that should prevent this from happening.
You can create one in a number of ways. For example: On Windows, if you open Notepad, then with a blank file go to File -> Save As, change the 'save as type' field to 'all files' and name the file .nomedia, you could place that in the folder on your Android device.

I hope this helps!