Some UEI protocol executors are "mini-combos". This means they support more than one device number within one setup code using single-byte hex commands. There will be more than one possible EFC number for each OBC number. DecodeIr can't determine the correct EFC number by looking at the IR signal, because it isn't a characteristic of the signal. It is a characteristic of the fixed data used in creation of the setup code.
DecodeIr will list two or three different EFC numbers for each OBC number. The sequence of those two or three EFC numbers is consistent across all the decodes. So once you find out which position in that list is correct for one OBC of a given device number and setup code, that position will be correct for the EFC list of any other OBC of the same device and setup code (except that for RC-5 the decision of whether or not the OBC number is above 63 is treated as being part of the device number).