Guild Wars 2

Just wondering, how does it react when you have multiple of them open, does it do one of these reactions?
- keeps at 50% redirected
- 50% for one, 25% for another, 12.5% for the third?
- 50% and 50% for another = 100% (doubt it)

The damage reduction on you stays at 50%. One of the defenders will randomly get the damage transferred to it.