It depends on what particular stat you're wanting to maximize. If it's DPS then Numinous Nimble Symbol of the Skeptic is your best bet with 52 base damage. Just search for Numinous to find all of the possibly best slot 11 augmentations.
EDIT: And yes, you can have 2, since there is no LORE tag on it nor the type 11 augs, they can be exactly the same other than the slot 7 augs will probably have to be different, as most are LORE.