After completing this quest I received the ring of Hircine. A very long time later I was rummaging through the Falkreath barracks and stumbled across Sinding, in werewolf form, in the jail cell we met him in earlier. I did not mess with him for fear of glitching the game. I quickly felt the barracks and was soon confronted by Sinding outside. He attacked me and I killed him quickly. I tried to search the body and could only tear his skin off. Upon during this Hircine appeared and rewarded me with the savior's hide. I now have both the savior's hide and Hircine's ring in my possession and in working order.

I get both, too. There is a known method for this posted in the notes section of this page: http://www.uesp.net/wiki/Skyrim:Ill_Met_By_Moonlight

Interesting. I just read the notes. I had no idea, I just stumbled across it.

This "Glitch" allows you to save Erandur, but still get the achievement for obtaining 15 Daedric Artifacts. Totally worth exploiting it.