Falling blocks can be duplicated with the End portal

The Bug

Falling blocks can be duplicated when falling in the end portal.

How to reproduce

Set an end portal block, place a fence below it. Place a certain number of gravity blocks above it. Break the base block and let them drop into the portal by gravity. See video 2020-04-24 15-59-49.mp4

→ Although only 10 sand blocks went through the portal, 14 are collected on the other side.

Original Description

If you have a little bit of luck, and the Dragonegg falls through the Enderportal, it will be duplicated.

1. Put the Dragonegg on top of the Enderportal which you got for killing the Enderdragon.
2. Make a right-click on it.
3. If it teleports above the portal and falls through, it will duplicate.

I uploaded a 30-seconds-video on YouTube showing the Bug:
https://youtu.be/C45dt3HFNd4

Long video with explanation: https://www.youtube.com/watch?v=IkfUHx18uLw

Code analysis

See MC-201882