EndPortal: Portal Physics blocks duplication

Video: https://www.youtube.com/watch?v=nwwpIhOhbMs
/////////////////////////////////////////////////////////////////////////////////////
Steps to reproduce the bug:
-----------------------------------
1: Go to the End and beat the EnderDragon
2: Place sand/gravel/Dragon Egg 2 blocks above the portal block
3: Go to your End world spawn point (the obsidian platform) and you should find the dropped block that you chose and a placed one