If there are 2 orders of the same price, you will sell the amount of the smaller order, but when you accept it the amount will be taken from the larger order, leaving the smaller order in tact, forcing you to trade only the smaller amount each time.

I had this problem when selling some of my ammo on my alt to liquidate his assets.  It was annoying even though it only made me do like 5 sales.  Imagine doing hundreds to be able to sell to an order completely.

Exploit:  set up orders for the exact same price as a large order but do only 1.  The seller sells 1 each time but it sells to the large order, never fulfilling yours.  Hilarity ensues.

Wohoo!