Doors act as tools

As the title say, the door has been acting weirdly to me.
When I crafted, everything was normal, but then, when I placed a door, it showed block durability, just like a tool should show when used. After I placed it in chest, it didn't stack. Here is a screenshot of what is going on to be clear:

Update:
Mining with a stack of doors decreases the durability of all doors in the stack.