DGR 22.214.171.124.4 does not refer to any limitations in the number of signatures. DGR 126.96.36.199.4 does state that the information to the pilot-in-command must include a signed confirmation or some other indication, from the person responsible for loading the aircraft that there was no evidence of any damage to or leakage from the packages loaded on the aircraft.
Following this requirement, all airlines have a statement preprinted on the NOTOC form reading: “There is no evidence that any damage or leaking packages containing dangerous goods have been loaded on the aircraft”. The NOTOC form is signed by the person responsible for loading and thus satisfies DGR 188.8.131.52.4.
A specimen of the NOTOC form is shown in IATA Airport Handling Manual however the form itself is left for individual airlines to design as it must fit the operational differences of each airline. The NOTOC form therefore may differ with each airline. DGR 9.5 specifies what items must be shown on the NOTOC. The format of the NOTOC form is left for each airline to decide.
The Captain and the person responsible for loading are obligated to place their signatures. The NOTOC form is handled generally in a similar manner but the processing may differ with each airline.