Can a Rogue gain sneak attack damage more than once per action?

Question

When my Rogue uses Circling Predator, he gets to attack twice:

Hit: 1[W] + Dexterity modifier damage.
Effect: You can shift 1 square and must end adjacent to the target. Then make a secondary attack against it.
Secondary Attack: Dexterity vs AC
Hit: 1[W] + Dexterity modifier damage, and you gain combat advantage against the target until the end of your next turn.

If the Rogue has combat advantage and no special feats does he gain sneak attack damage for each separate attack?

Or can sneak attack only be applied to one attack per turn/round?

Answer 1

You may only apply Sneak Attack once per turn

However, you may apply it whenever you wish in that turn, so long as you meet the conditions:

When you make an attack with a light blade, a hand crossbow, a shortbow, or a sling and hit an enemy granting combat advantage to you, that enemy takes extra damage based on your level (see the Sneak Attack table). You can deal this extra damage only once per turn.

Given that all uses of powers and class features tend to be optional unless otherwise stated, there is no reason why you cannot take SA on either attack. If you have Slaying Action you may apply it on a second action granted by sneak attack. There are a number of powers that grant sneak attack damage as well.

Answer 2

According to page 117 of PHB1 under Sneak Attack

Once per round, when you have combat advantage against an enemy...

So you'd only get sneak attack damage for the first attack that hits.

If you are to go with the errata at WotC website, you may deal damage once per turn.

Answer 3

Yes (to either attack but not both)
As everyone has pointed out, you can get sneak attack once you have combat advantage but only once per turn.

No (to the second attack)
If your combat advantage comes from being hidden or invisible, you cannot apply your sneak attack to your second attack because you will not have combat advantage after your first strike.

Might I suggest Quickhit Bracers (Adventurer's Vault pg118) and Shadowdancer's Gloves (Adventurer's Vault 2 pg105) that will give you an extra 2d6 of damage for that turn.