Unequipping the Crudest Boots no longer seems to dismiss/resummon your Mystic Ally, resulting in the permanence of the “duplicate” Ally.
Even upon casting the Active Ally, or killing them in battle, it seems to remain indefinitely.
On Live servers, unequipping The Crudest Boots immediately removes the duplicate Ally.
EDIT: Note, this is irrespective of Inna’s set bonuses, and happens even without Inna’s being equipped.