[Quiet Man Cometh]

You can donate them to new people that join after said events, or give stuff to Cat Paws for that purpose. Event items are put into bundles usually, so you don't usually need more than one unless you want two of a particular item. For instance I have two Zara's bundles from Nox so that I can wield two spears, but I don't necessarily have much use for two of the other items in the set, except for the sake of keeping the set together if I sell it in the future.