How it Works
This setting helps prevent uploading duplicate images to Shopify by comparing cached images to images being uploaded to Shopify.
Where to Find
This setting can be located within the advanced settings of the Publish Listings page.
Use Case
If you are caching your images and you are know you have products that use the same image then you should enable this setting, so Shopify only receives one link for the image. This allows for your product pages to load quicker because it will only have to download one instance of the image and not multiple.