As far as I know the answer is not, you can not anylonger imbue an item with the same elemental protection that it already has. Never heard that the falcon set were different about it. And about the Umbral master spellbook, you can imbue it with death protection.
What it is more, you are neither allowed to imbue an item with an elemental protection that this item has a weakness for. For example:
- Gnome armor (Arm:17, distance fighting +3, protection physical +4%, energy +8%, ice -2%).(Empty Slot, Empty Slot).
This armor only allows you to put: death, earth, fire and holy protection on it (life leech too), because it gives you protection against energy and weakness against ice)