If an ability is linked to a second ability, copies of that first ability are also linked to that second ability. If the second ability refers to "the exiled card," it refers to all cards exiled by the first ability and the copy. For example, if Clive's Hideaway's hideaway ability is copied and two cards are exiled, you may cast both exiled cards without paying their mana costs (assuming you control four or more legendary creatures at that time.)