I dont think I understand this questions. I was under the impression that the unique Yoda units would swap.
So you have the "old" Yoda in play. You use the event to search out the "new" Yoda. Since you cannot have two copies of unique cards in play. I thought the "old" Yoda would go to the discard pile and the "new" Yoda would come into play (after you pay his cost)
The other flip side is, what if you play the event to search out Yoda but cannot pay his cost to play him. Would he go into the discard pile and then suffle your deck? I dont believe this even allows Yoda to be played for free (or put him in your hand). You must play him and pay his cost as well. Correct me if I misunderstood this.