Example solution: You assume that the UI/marketplace you're viewing the NFT in doesn't do this for you. If something is sufficiently famous (ie the artist is w

Example solution: You assume that the UI/marketplace you're viewing the NFT in doesn't do this for you. If something is sufficiently famous (ie the artist is well know to the UI) it's trivial to validated that an NFT is made by one of those artists and have the equivalent of a twitter blue checkmark. For stuff that's not sufficiently famous, then the question of duplicates is probably not a real problem. Who cares if someone copies a <$1 digital asset. And if the artist ever becomes famous and is back-filled into the UI's known list, then all their previous works gain the blue checkmark. These UI's will probably have a few centralized winners (which is why VC's fund crpyto startups) but there can be a long-tail of decentralized UI's as well. How much you care about authenticity will guide you to which UI's your willing to use.