So, I had this happen a couple times and IDK if it's a glitch? Well first off I'll say this.. I've done all of the Whiterun Bounties.. twice.

Don't really know how, it was kinda cool cause I got 2 sets of 4 Lunar Weapons lol. Anyway, I went in there cause I haven't in a long time (Bannered Mare) and she gives me a bounty to kill the giant at BB.

Weird thing though is I already have it "Cleared." on my Map and already discovered. And when I hit "Show on map" it does nothing. Can I still go kill the Giant.. again I guess?

EDIT: MY BAD, thought I was posting in the Hints section... please move appropriately! ^.^

My bounty quests are still glitched in winterhold, it tells me to collect bountys that I`ve alrdy collected. But as for clearing bounties that you have alrdy cleared. You can do so, I`ve cleared the dragon by whiterun.. prob... 3 times. Each time someone told me to go clear it, I did, get reward, couple days later they want me to clear it again, do it get reward etc etc. lol I`ve also cleared numerous giant bounties over and over again too

My only gripe with the bounty system right now, is that I have to kill the giant in Bleakwind Basin, and...there is no giant. Quite a common bug, but I'm sure it'll get sorted out. No big deal.

Has happened with me in Valtheim Towers and Bonestrewn Crest. The bandits and dragons have not respawned in this region. Despite almost 100 game days passing without me setting foot near these areas. I also can't actually recieve bounties from Riften, Solitude or Winterhold. No matter who I speak to the option for work just doesn't come up at all . I also can't go to Dawnstar as the "Collect your payment from Brina Merelis" message does not clear. I now have two identical statements locked in my journal.