Indeed, hashes are only guaranteed to be unique for a given "top-level entity". Hashes are unique for item definitionss, and unique for vendor definitions, but not guaranteed to be *between* vendors and items. Also, as Rikkert2x pointed out, definitions of entities are uniquely identified by their hash, while actual instances of entities are identified by other "Id"s (which only really matters at the moment for Accounts, Characters, and Items) Also note that hashes for non-top level entities are not guaranteed any sort of uniqueness outside of whatever they are contained within. For instance, Talent Nodes have hashes, but they are only unique within that specific talent grid. (they also are subject to version dependency. You should only trust version independence in top-level entities as well)