You can swap various 6L6 tubes between different types of the same style. Keep in mind that you cannot replace 6L6 tubes for 6v6 tubes, for example, but instead can exchange diverse brands of the same type of tube. Swapping entirely different types of tubes could cause damage to the tubes themselves or to the amplifiers. Interchanging brands will not damage your amplifier and will negligibly affect the audio and ability of the system.