Tag file if name exists in other folder?

[RAMillu]

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"

[Mr_Noodle]

Since it looks in two different folders, you'll need a script to do that.