Quest mob and Efreeti both up in quest room
 

This should not be possible. triggering the quest giver should despawn the Efreeti. On top of that, Will has there for quite a long time based on my track (oldest mob in range).

https://imgur.com/Q0qO48d

Fixed, pending update

This happened on Red (not sure if your image is from red - happened to be same NPC).

Wrong book was handed in, depopping Efreeti, then quest NPC was NOT used. X hours later Efreeti re-popped, and it stayed that way since.