Does the storm troopers 'squad training' ability stack? For instance, if I have two storm troopers adjacent to a trooper that is attacking does the attacking trooper get to reroll two attack dice? Thanks in advance for any responses.

Great question.

The condition is "while attacking, while adjacent to another Trooper", so it would not matter how many troopers you were adjacent to, you would only re-roll one attack die.

Squad Training is an ability on the figure that is attacking, it is not granted by another figure like the Royal Guard Protector ability.

Therefore, as the ability say, "You maye reroll 1 attack die"

Now that I actually LOOKED at the card, I agree with Hatting. Will adjust my answer.

Hi and sry about my english but I do not understand the actual outcome...

Does this mean that this trooper may use his ability twice on different adjacent troopers to reroll two (by rules different) dice?

As long as there is one or more adjacent trooper(s), the attacking trooper may reroll one (and only one) attack die.