If it was a duplicate they would be able to show how the hash of the duplicate report was already in the tree. For more information you might want to read about

If it was a duplicate they would be able to show how the hash of the duplicate report was already in the tree. For more information you might want to read about Merkel proofs. For example here: https://www.quora.com/Cryptography-How-does-a-Merkle-proof-actually-work https://www.quora.com/Cryptography-How-does-a-Merkle-proof-a...