Undoing a group duplication creates broken objects

[Cart3r1234]

What are you trying to do, and what do you expect to happen?

In the process of duplicating groups, I undid a duplicate action, which should have removed the duplicate group and cube. It did not properly remove the duplicated objects, and left some in a broken state.

What happens instead?

Instead of being removed when undone, I was left with the cube that was duplicated still in the workspace, but it and the group it belonged to were no longer present in the outliner.

Steps to reproduce:

1. Create a group with a single cube in it.
2. Select the group (not the cube)
3. Duplicate it twice. Notice how the selected objects in the outliner are not what you'd expect, being the original group plus the duplicate cubes in the duplicate groups
4. Undo twice. You are left with 2 cubes that do not show up in the outliner. Nothing done to these cubes will make them show up in the outliner, and duplicating them causes the duplicates to also not be shown.
   Alongside cubes that don't show up in the outliner, I've also had the undo action remove only the group and leave behind the cube.

Model format in which the issue occurs

Generic

Blockbench variant

Program

Blockbench version

4.12 Beta 2

Operating System

Windows 11

Installed Blockbench plugins

No response