I don't think it's a bug. It's just.. region is randomly selected, so it's possible to get several quests on the same tile. Extremely rare tho. Try to just do them, as kuba said.
Happened to me also once. 1 NM and 1 hard on same region. Hard was displayed in first "row" (the NM under it, which you cant see). First quest was with NM AI -> received hard quest reward. Second also with NM AI -> received NM quest reward.