Entities will duplicate when player enters/exits the nether in snapshot 19w09a.

When I come in and out of a nether portal, i would go to check on a little pen. This pen would have started with one baby chick, and when i looked next time, there were seven. I have no idea what is going on. The same thing seems to happen with item frames including the items inside them; the items would be on the floor in large quantities.