Anvil destroys Buttons when placed in the same block

I was fiddling with a little machine i built to drop anvils on a mob when I accidently placed an anvil into the same block-space the button was occupying

Tested in All game-modes except hardcore

What I expected to happen was...:
The anvil to be placed in the block next to the button

What actually happened was...:
Instead, it removed the button without an item-drop, taking its co-ordinates

Steps to Reproduce:
1. Place a block down (In my world it is sandstone)
2. Place button on block (stone & wooden are affected equally)
3. Place anvil onto the block below the block that the button is in (As seen in the included image)