Although this may have it's own problems, I think it would be beneficial for multiple links to be added to a specific photo.
For example, look at pixel-perfect duplicate. Many of the photos are exactly the same as the original one posted, yet it has a different link so we're still able to publish the photo here.
This system would be for pixel perfect duplicates only, and wouldn't include simply duplicates where the photos are different sizes.
For a further example, I've posted a duplicate that's the same size on my own: post #5467316.
Notice how this one was posted to Pixiv. Because it was published to Pixiv, I was able to post the exact same photo that was posted in post #5459644 - which is the exact same photo in every regard including pixels, but was originally posted on Twitter by the same artist.
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