I think Excluded prevents one ancilliary to be used with another. The example seems redundant, if he´s got the Unique attribute that per definition excludes the use of the same ancilliary again (however, it makes sense for generic ancilliaries, to prevent having, say, two biographers on one character). As well, there are some ancilliaries that can´t go together, I don´t have an example in mind, but I know there are.