Aegon's Hill can be triggered in challenges to look at an opponent's hand and put one of his character cards into his dead pile.
1) Assuming that a unique character is chosen, does that mean I will not be able to marshall the character in future even if I have additional copies in my hand/deck?
2) In the scenario that the character chosen is one I already have in play, I presume there's no impact other than I lose a potential dup for him?