UI Builder appends a duplicate attribute in AttributeOverrides when re-editing an override on an element whose name contains a space

How to reproduce:

1. Open the attached "IN-148895" project
2. Open "Main.uxml" in UI Builder
3. In the UI Builder Hierarchy, expand "Main.uxml">"TemplateContainer" and select the "Thin g" element
4. In the UI Builder Inspector set "Title Text Size" attribute to any value and press Ctrl+S
5. Change "Title Text Size" attribute to a different value and press Ctrl+S
6. Observe the Console window and “Main.uxml” code

Actual result: Second save appends a second title-text-size to the <AttributeOverrides> tag instead of replacing the first, producing invalid UXML that then fails to import with XmlException "'title-text-size' is a duplicate attribute name"
Expected result: Second save replaces the existing override value, so each attribute name appears only once in <AttributeOverrides>

Reproducible with: 6000.0.0f1, 6000.0.81f1, 6000.3.21f1, 6000.5.7f1, 6000.6.0b7, 6000.7.0a4

Reproducible on: Windows 11 (25H2)
Not reproducible on: No other environments tested

Workaround: don't put spaces in the name of any element you override via Attribute Overrides - a name with no spaces (e.g. "MyThing") replaces the value correctly instead of duplicating