Breaking 1 wooden door gives 2

Today,When I Remove my wooden door to place on other places of my house,
the only wooden door when break,it gave me 2. When I tried using the stone axe, it destroyed it.

I thought that when a wooden door is break by me,it should only gave me 1 instead of 2 and when
using the stone axe makes breaking the door faster than bare hands and not destroying it.

I tried using 3 materials

1.Stone Axe
2.Iron Ingot
3.Bare Hands
The result was that when I am using the stone axe,the door disappear after breaking it.
The other 2 when breaking the door,it gave me 2 doors instead of 1
I am using iOS 4.3.3 on the iPad 2