dnd 3.5e – Does rogue’s vest bonus damage apply separately for each precision damage source?

Rogue’s vest (MiC 130) grants users with “the skirmish, sneak attack, or sudden strike ability” an extra 1d6 damage “when making such an attack”

Does this mean that, for example, a scout 1/rogue 1/ninja 1 that moves 10 feet and attacks a flat-footed opponent (who lacks uncanny dodge) deals 1d6 base skirmish damage plus 1d6 extra damage because they made “such an attack”, as well as 1d6 base sneak attack damage plus 1d6 extra damage for making “such an attack” and 1d6 base sudden strike damage plus 1d6 extra…For a total of 6d6 precision damage? Or is the “attack” only granted the item’s bonus damage once, for a total of 4d6 precision damage?