I would like to store images in two separate locations and make sure there is no overlap. Ideally, this would extend to images that were the same but different

I would like to store images in two separate locations and make sure there is no overlap. Ideally, this would extend to images that were the same but different sizes, etc but not extremely pressing. One of the images stores will come from scraping and I would like to compare it to see if the same image already exists on my server.