"Assembly with name already exists" errors are thrown when two packages with different technical names resolve to the same namespace

Steps to reproduce:

1. Create a new URP project
2. Go to Window > Package Management  > Package Manager
3. Click on the + > Create package...
4. Create a package with the display name "my package"
5. Create a second package with the display name "my-package"
6. Observe the Console

Actual results: Multiple "Assembly with name '...' already exists" errors are thrown. Both packages dedupe correctly at the technical/folder level (com.[org].my-package vs com.[org].mypackage) but their namespaces both collapse to the same value (e.g. Org.MyPackage), so every generated .asmdef (Runtime, Editor, Tests, Editor.Tests) shares an identical assembly name

Expected results: Namespace/assembly-name conflicts are resolved gracefully the same way technical-name conflicts are, by appending an incrementing suffix (e.g. Org.MyPackage, Org.MyPackage1), so each package produces unique assembly names without errors

Reproducible with versions: 6000.0.0f1, 6000.3.18f1, 6000.4.12f1, 6000.5.0f1, 6000.6.0a7

Tested on (OS): macOS 26.5, Ubuntu 24.04

Notes:

• The two packages get different folder names (com.[org].my-package and com.[org].mypackage), so at first it looks like the duplicate-name handling worked. But both display names get converted into the same namespace (Org.MyPackage), and the assembly names come from the namespace, not the folder name. That's why you get duplicate assembly errors even though the folders are different