induction ls; simpl in *; intuition.
destruct (in_dec _ a (getUnique ls _)).
right.
eapply IHls.
eapply H.
simpl in *.
intuition.
right.
eapply IHls.
eapply H0.
Qed.

(* Specifications: *)
Theorem in_getUnique : forall (A : Set)(ls : list A)(eqd : eq_dec A) a,
In a ls ->
In a (getUnique ls eqd).