I need to confirm my belief about defending 2 different attacks on same Hero, can a single Hero defend twice in the same combat phase with 2 copies of Unexpected Courage (in my case on Beregond with Sentinel)? I say you can.

The short answer is yes.

The longer answer is that for each attack, if your hero is ready and otherwise generally seems eligible (eg controlled by the right player or has sentinel) then they can be declared as a defender, regardless of whether you have defended other attacks and regardless of whom those attacks were from. This is is true regardless of how you came to be ready.

Unexpected Courage is a very popular way to achieve being ready for this purpose and thus get multiple uses out of one of your better defenders (eg Beregond or Erkenbrand). Armored Destrier is also a fine choice for achieving this.

Of course, you only need one unexpected courage to be ready for a second attack, but with two of them, you could defend three times.