Question on eidolon orbs.

I have roughly 10k orbs, but not really sure what would make most sense to buy from eidolon orb shop. I'm assuming the main thing to buy is SSR dragoons, but not sure if it makes more sense to get a duplicate (I have 1 for water and wind) or for an element I don't currently have one. For reference, my main eidolons currently are (in element order): Belial, Tiamat, Icarus, Tartarus (/Amaru/Girimehkala- need to do the math on which would make most sense), Yule Goat, and Echidna (yes I'm aware SSR dragoons don't go in main slot, just listing in case they should be replaced with 40/20 eidolon). I could see the argument for getting Jormungandr, Quetzal, or Thunderbird/Yggdrasil, but I just feel like getting the dragoon could help so much more. Thoughts/comments? Also random question, if you get 2 SSR dragoons of the same element, can you just equip both of them to have more uptime on the buff instead of break limiting them?

tl;dr: atk/hp eidolon or dragoon from orb shop, and if dragoon duplicate to break limit or 1 of each element first?