How would that work? Surely the company could make a fake duplicate and show it to you in a Merkle tree as "proof"? They literally make up every node in the Merkle tree after all.
They could publish a hash of the whole existing tree regularly.
Exactly. After every submission in fact.
Well no, they’d have to publish all reports which most companies don’t like doing because it makes them look very bad.
They wouldn't have to by the nature of how a Merkel tree works.
Could you elaborate precisely how this scheme works to stop a company claiming reports are duplicates when they’re not?
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-a...