Apfelstrudel

I do also recognize this bug. It is possible to get the reward amulet as often as I speak to Kaenra. I did the same as LilSassy except I didn't return to Keanra but killed the wizard directly after speaking to real Purnisc. I realized another thing: I finished the quest before the patch 1.03 was released. If I remeber right, Kaenra left the tavern after I spoke to her. Then I somewhen installed the patch and continued playing. I was surprised seeing her a little while ago and being able to complete the quest because I was sure I already finished the quest.