Description

It seems that when you duplicate a template part, it does not automatically receive a unique identifier?

In the site editor, when I duplicate a template part:

1. The title of the copy remains the same as the original
2. When I add blocks to the copy, the original template part is also updated. -Hence I can not edit the copy without also changing the original.

-I can not change the title of the copy without using "Update design." #29844
-After changing the title of the template part and updating, the template parts are separate.

Step-by-step reproduction instructions

Please list the steps needed to reproduce the bug. For example:

1. Activate a theme with support for full site editing.
2. Open the site editor. Create and duplicate a template part.
3. change the contents of either template part.
4. confirm that both template parts are updated when you edit one of them.

Expected behaviour

I expected the copied template part to be its own unique copy with a new, random slug/title

Actual behaviour

The template part is not "unique" until the title has been updated by the user and the changes saved.

Screenshots or screen recording (optional)

WordPress information

• WordPress version: 5.7
• Gutenberg version: current trunk at f1d9a0b
• Are all plugins except Gutenberg deactivated? yes
• Are you using a default theme (e.g. Twenty Twenty-One)? Empty theme

Device information

• Device: Desktop
• Operating system: Windows 10
• Browser: Chrome Version 89.0.4389.90