Multi select is not handled correctly when exporting Packages in the "Project" window

Steps to reproduce:

1. Create a Unity project
2. Go to a "Project" window
3. Select "Packages"
4. Right-click and select "Create UPM Package..."
5. Enter the package name "Test" and click the "Create" button
6. Create one more custom "Test2" package in the same way
7. Return to a "Project" window
8. Find newly created "Test" and "Test2" packages
9. Select them both
10. Right-click and select "Export -> Export Package..."
11. In the "Export Package" pop-up, select org and click "Export"
12. Select the location where the packages should be exported
13. Open the selected location and observe the result

Actual results: Only one package is exported

Expected results:  All the selected packages should be exported

Reproducible with versions: 6000.5.0a7

Not reproducible with versions: We can export UPM packages in 6.3+ only.

Tested on (OS): macOS - Tahoe 26.3