Tag file if name exists in other folder?

Would it be possible to tag a file "blue" fore instance, if name exists in other folder?
example if folders look like this:
folder A/
img_1.jpg
Img_2.jpg
img_3.jpg
folder B/
img_2.jpg
then:
img_2.jpg in folder A should be taged "blue"
example if folders look like this:
folder A/
img_1.jpg
Img_2.jpg
img_3.jpg
folder B/
img_2.jpg
then:
img_2.jpg in folder A should be taged "blue"