Plagon + Flicker Creature + ETB Doubling Effects

Hi, if I have Plagon, Lord of the Beach + a doubling effect like Elesh Norn, Mother of Machines in play, and then I play Restoration Angel, is it possible to stack the mechanics so that I get to blink Plagon two times (for 4 ETB total)?

Wasn't sure if I have to declare target for both instances of Restoration Angel etb effect before I can resolve one Flicker, which would make one of the blinks lose its target