Minecart with hopper duplication bug

What I expected to happen was...:
I thought that the two minecarts with hoppers would just pick the item up

What actually happened was...:
Both of the minecart with hoppers picked the item up, and duplicated them

Steps to Reproduce:
1. Build a parralel rail, with powered rails to power it
2. Put down the two minecarts with hoppers, one on each rail
3. throw and item between the tracks, in front of the minecart path
4. Activate the powered rails, so the minecarts will both reach the item at the same time
5. You can also just throw and item between the two minecarts
6. Sometimes you have to save and exit, then come back to the level for it to work