Bug: Hopper minecart will suck items from another hopper minecart that is one block above but one block over horizontally (effecting super smelters)

To reproduce:

1.Place an input (chest or hopper) above a hopper minecart.

2. Place another hopper minecart one block to the side and one block below the other hopper minecart.

3. Put items into input chest

Result: The items will drain from the chest, through the below hopper minecart (though you can not see them pass through) into the other hopper minecart. This will also cause lag, making opening the bottom hopper minecart inventory difficult. Also happens when the hopper minecarts are running in tracks and past each other in this way. I have attached a video of this happening on my small super smelter. The pause near the end before I open the bottom hopper minecart inventory is caused by lag. Single player world.