MSIX publish (APPX1101 duplicate .pdb) regression when Visual Studio 2026 is installed alongside Visual Studio 2022

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### Describe the bug

### Description

I’m reporting a regression affecting MSIX publishing (APPX1101 – duplicate payload, typically `.pdb`) that appears **only after installing Visual Studio 2026 alongside an existing Visual Studio 2022 installation**.

The exact same solution builds and publishes correctly before VS 2026 is installed, and starts failing immediately after. Removing VS 2026 and repairing VS 2022 restores the original (working) behavior.

This strongly suggests a shared toolchain / MSIX packaging regression introduced by Visual Studio 2026 components (MSBuild / WindowsAppSDK / MSIX targets) that impacts Visual Studio 2022 builds.

### Why is this important?

### Regression evidence (very important)

This behavior is reproducible through environment changes only:

1. ✅ Visual Studio 2022 installed alone
→ MSIX publish succeeds

2. ❌ Visual Studio 2026 installed alongside VS 2022
→ MSIX publish fails with APPX1101 (duplicate .pdb)

3. ✅ Visual Studio 2026 uninstalled + Visual Studio 2022 repaired
→ MSIX publish succeeds again with no project changes

No source code, project configuration, or dependency changes were made during this process.

### Steps to reproduce the bug

### Environment

- Visual Studio 2022: 17.14.x (Stable channel)
- Visual Studio 2026: v18.x (installed later; exact build available if required)
- Project type: .NET MAUI (Windows target)
- Target framework: `net9.0-windows10.0.19041.0`
- MSIX packaging enabled
- Runtime identifier used: `win10-x64` (via `RuntimeIdentifierOverride`)
- Windows SDK: Windows 10 (19041)
- OS: Windows 10/11 x64

### Actual behavior

### Actual behavior

After installing Visual Studio 2026, publishing fails with:

APPX1101: Payload contains two or more files with the same destination path '*.pdb'

The error originates in:
`Microsoft.Build.Msix.Packaging.targets`

The failure affects multiple referenced projects (common libraries), even though only a single `.pdb` exists per project output.

### Expected behavior

### Expected behavior

Publishing the MAUI Windows project as MSIX succeeds, as it did consistently before installing Visual Studio 2026.

### Screenshots

_No response_

### NuGet package version

From Version 17.14.30

### Windows version

_No response_

### Additional context

### Environment

- Visual Studio 2022: 17.14.x (Stable channel)
- Visual Studio 2026: v18.x (installed later; exact build available if required)
- Project type: .NET MAUI (Windows target)
- Target framework: `net9.0-windows10.0.19041.0`
- MSIX packaging enabled
- Runtime identifier used: `win10-x64` (via `RuntimeIdentifierOverride`)
- Windows SDK: Windows 10 (19041)
- OS: Windows 10/11 x64

### Related issues

This appears closely related to existing APPX1101 duplicate payload reports, such as:

- https://github.com/microsoft/microsoft-ui-xaml/issues/9634

However, this report adds a new dimension:
the error is triggered purely by **installing Visual Studio 2026**, even when building and publishing from Visual Studio 2022.

### Additional notes

At the moment, the environment with VS 2026 installed is no longer available, since uninstalling it was required to restore production builds.

If necessary, I can:
- Reproduce again in a controlled environment
- Provide exact VS 2026 build numbers
- Capture MSBuild binlogs during failure

Please let me know how best to assist further.

Start by reproducing the publish failure in the documented Visual Studio 2022-only and VS 2022 plus VS 2026 environments, then capture the requested MSBuild binlog. Inspect Microsoft.Build.Msix.Packaging.targets and compare the payload inputs around the APPX1101 duplicate .pdb error. Done means identifying the regression source or confirming which toolchain component owns it.

Written by the indexing model from the issue text.