The description for the miniquest after Dealing with Scabaras (gathering research notes for the archeologists) states that duplicate notes can be dropped. However, the enemies will only drop notes that have not been added to your 'scabaras research' journal - if you use the notes as soon as you get them, before killing another creature, then you will not receive any duplicate drops. You'll only get duplicates if you don't add them to your journal right away.

 

Also you might want to mention (in the main part of the walkthrough or in the miniquest portion) that one good spot to kill enemies for research notes is the swamp area just east of the plateau - in the swamp, you don't have to drink water constantly, and there's a small number of scabarites that can easily be trapped and killed one at a time. Also they do become non-agressive if you stay there long enough, which makes things easier - the locust-riding ranger seems to be the easiest to kill of the group, if you get to that point.

Hey Sorator, sorry for the delayed response,

I've added this information about duplicate drops into the guide, as well as a tip about the swamp creatures. Thanks so much for taking the time to submit this information! You've been credited.

 

~Wmx