linux-pipewire: Forbid screencast source duplication

[tytan652]

Description

Each instance holds a unique session with a unique restore token. Which both can not be duplicated.

Motivation and Context

@mihawk90 reported issues with those in Studio Mode with "Duplicate Sources" enabled, which revealed bugs due to the unique nature of each instance of those.

How Has This Been Tested?

Locally, the source is no longer duplicated in the in Studio Mode with "Duplicate Sources" enabled.

Types of changes

• Bug fix (non-breaking change which fixes an issue)

Checklist:

• I have read the contributing document.
• My code has been run through clang-format.
• My code follows the project's style guidelines
• My code is not on the master branch.
• My code has been tested.
• All commit messages are properly formatted and commits squashed where appropriate.
• I have included updates to all appropriate documentation.

[mihawk90]

For reference, the issue at hand is this:

Screencast_20260720_074301.webm

[RytoEX]

@mihawk90 Does this fix the behavior you encountered?

[mihawk90]

I haven't been able to build it yet, will probably get around to it in ~2h or so and will report back

[mihawk90]

Yes works as expected. Only one screencast indicator and the transition happens instantly.

Can also still manipulate in Preview without affecting the Program.