can they be found only once? meaning if I already have the 2 blues from the troll artifacts, I have a "higher" chance to get the sword now ?
thank you in advance
Yes that's correct; and also since 4.1 if you find all the rares in a race, you have a lower chance to pop that digsite (thus a higher chance to pop others), so if you're farming for something specific, it will help you to complete all rares in the other races too as it'll increase the dig site chance for the one you're looking for.