What does the "2 Rolls mean" on the Deep Dive reaction?
In the 2nd Edition rules, there's nothing that say "2 Rolls", but you do take a roll against your U-Boat's Evasion Rating after the Escort attacks to see if you have successfully avoided the attack. If you succeed you only receive 2 Stress, and if you fail you either receive Flooding, or a Hull Hit. You do not take the normal damage from the Escort's attack (Hits as written on the Escort card).
Here's from the 2nd Edition rules:
When a U-Boat uses a Deep Dive do the following:
Place a Deep Dive counter on the U-Boat counter.
Add 2 Stress Points on its card.
All Escort attacks have no effect, but roll a die. If
the die roll is equal to or less than the U-Boat’s
Evasion rating, there is no effect.
If the die roll is greater than the Evasion rating, the
U-Boat takes one Flooding Temporary Damage hit.
If the die roll is 10, the U-Boat takes one Hull
Lasting Damage hit.