My personal opinion is that BatBrain shouldn't assume all monster images are unique. Alternately, should KoLmafia provide a way of telling if an image can disambiguate to more than one monster?
Each monster has a list of images accessible via proxy field.
Internally, we have a map of images to monster which goes from the first listed image to the first monster with that image.
That is the data source for image_to_monster( string).
I suppose we could change our internal map to map ALL of the images for every monster into a list of all the monsters that have that image - and the first one would be as before.
We could then make
boolean [monster] image_to_monsters( string)
to get all the monsters. If the map has only one key, the image is unique.