[Phil^]

worked example :

51 coins, 11 are heads = 40 tails

Take one coin, its heads. Flipped and is placed into pile 1.
1) T , 2) 10H,40T
Take one coin, its tails. Flipped and is placed into pile 1.
1) T,H , 2) 10H,39T
Take one coin, its tails. Flipped and is placed into pile 1.
1) T,2H , 2) 10H,38T
Take one coin, its heads. Flipped and is placed into pile 1.
1) 2T,2H, 2) 9H,38T.
Take one coin, its heads. Flipped and is placed into pile 1.
1) 3T,2H, 2) 8H,38T.
Take one coin, its heads. Flipped and is placed into pile 1.
1) 4T,2H, 2) 7H,38T.
Take one coin, its tails. Flipped and is placed into pile 1.
1) 4T,3H, 2) 7H, 37T.
Take one coin, its tails. Flipped and is placed into pile 1.
1) 4T,4H, 2) 7H, 36T.
Take one coin, its tails. Flipped and is placed into pile 1.
1) 4T,5H, 2) 7H, 35T.
Take one coin, its tails. Flipped and is placed into pile 1.
1) 4T,6H, 2) 7H, 34T
Take one coin, its heads. Flipped and is placed into pile 1.
1) 5T,6H, 2) 6H, 34T.

Both piles have 6 heads in them, fitting the requirements.