Do donated clan war troops spawn on both attacks?
The troops in the clan castle indeed defend each attack.
You can be attacked more than two times in a war, but your clan castle is always full for defending against those attacks, full of whatever was in the castle at the end of the war's preparation phase.
Additionally in war:
- Heroes are always active to defend your War village.
- Defenses like Xbows and Inferno towers, and traps are preloaded
- Any defenses under construction are active in war, unlike your home village. In fact, any defense STARTED prior to the end of preparation day is active and defends your war village.