Bug Duplicate prefab instances

Hi! We've been running into a bug with instantiating prefabs in the Editor. Often, a duplicate prefab appears in the hierarchy after saving and reloading the scene.

Ubuntu 16.04.1 in VMWare
Unity 5.3.4f1 and 5.4.0p1

To reproduce:
1) Create a simple prefab with a basic C# script attached
2) Create a new scene and drag the prefab into the hierarchy
3) Save and reload the scene
4) There are now two instances of the prefab in the hierarchy

Here's a video:

Thank you!

 

Thanks for the report - we'll investigate.

 

I would like to vote up this bug. I ran into it in Xubuntu 16.04 / Unity 5.4.1f1. I had my editor set up in columns, with the scene hierarchy in the far left, the #Scene tab in the middle, and the Project tab on the right. If I dragged a prefab from the Project tab across the 3D Scene window and to the Hierarchy, I would get two instances of the object.

What's really brutal is that the "extra" GameObject doesn't show up in the scene hierarchy until you restart Unity (edit: or reload the scene, I guess)--it just persists invisibly, causing mischief.

Fortunately if I instantiate a prefab by dragging directly into the 3D scene view, I don't observe the problem, so at least there's a workaround.

 

Same thing is still happening today, on my mac book unity 2020.21.f1

 

I'm trying this thing but it's not happened.