Every RFID chip carries two numbers. The EPC identifies the specific product and is assigned when the DPP is created. The TID is burned into the chip at manufacture and can never be changed.
Both matter: an EPC alone could in principle be copied onto a blank tag, but if that happened, the TID wouldn't match GCN's record — the copy would be detected. Not every tag on the market ships with a genuinely unique TID, so GCN independently tests suppliers rather than relying on spec sheets alone. Your DPP Package includes the specific TID information for the tags you choose.