Yes, you can. I've done it. If you have a surplus of coins and a burning desire to get a particular item from LFR, you can do that LFR instance as many times as you like and roll on that boss as many times as you like. Also, you can get 14 chances at loot from the same boss. Pool 10 coins, do the boss 10 times, and then turn in the coin weekly and do the boss three more times. Regular loot + 10 pooled coins + 3 coins from this week's weekly = 14.