I searched, but didn't find anything relating to this...
When i went and farmed dailies to fill up my 25 dailies to try to kill Coren Direbrew, I noticed when i had done all 25 dailies, that I could get the same daily again.
For example:
Daily yesterday was Black Knight's heart (hToC)
I did this daily first, then all the Argent Tournament Dailies, cooking/fishing, Quel Denas, and brewfest.
I had already turned in Black Knight's heart for hToC, but got the quest again.
This is great for:
When you're farming heroic achievements (say you failed Less-Rabi, and would rather go back and get 2 Triumph badges instead of just working towards the achievement)
When you really like the daily. (I love hToC, but really don't feel the desire to do hOculus)
When you're working for a specific item from a heroic (Tank trink off 2nd boss from hAN)
You might think it takes less time to just do another heroic, but for someone like me, who does way too many dailies every day, it just takes a quick trip to QD (20 minutes) to finish out the rest of your dailies.(daily bg/heroic&norm/Argent/Hodir/cooking/fishing)
If anyone can think of screenshots i could take to prove this, lemme know, and they'll go up tonight.