Tried-to-delete Built-in Attributes fail to get duplicated in VFX graph

Steps to reproduce:

1. Create and open a new project
2. Install the Visual Effects Graph in Package Manager
3. Create an Empty VFX asset and open it
4. Open Blackboard subwindow
5. Expand Built-in Attributes in Blackboard
6. Select one of the Built-in Attributes
7. Click 'delete' on the keyboard ("You cannot delete..." warning should be thrown in Console)
8. Click CTRL+D (to duplicate it)
9. Observe the Blackboard

Actual results: The Attribute doesn't get duplicated into Custom Attributes

Expected results: The Attribute gets duplicated into Custom Attributes

Reproducible with versions: 6000.0.0f1, 6000.0.82f1, 6000.3.23f1, 6000.5.11f1, 6000.6.0f1, 6000.7.0a3

Not reproducible with versions: 6000.7.0a4, 6000.7.0a6

Tested on (OS): Windows 11 Pro (25H2)

Workaround: Click the Built-in Attribute (or any other) again before step 7