The invention provides tube-filling machines and methods for, in such machines, end sealing of double tubes (10), that is to say the tube type which has concentric packing tubes (11, 12) which are connected to a common tube shoulder (13) provided with a dispensing opening. The invention provides a two-part hot-gas nozzle (22) with individual supply of hot gas to the inner side of the inner tube and the outer tube for thermal activation of the scaling end of the double tube intended for heat sealing.