Blender Version
Broken: 2.79, 2.81, ...
Worked: ?

Short description of error
when using Stereoscopy to render a scene from multiple cameras simultaneously, and using the compositor 'Switch View' node to save each camera output separately - unwanted files are saved with each output file.

Simpler version of the report

The combination of the switch view node, mix RGB node and rgb node is creating the problem, disabling even just one of those three nodes produces normal results.
The bug is reproduced only when all mix nodes are connected to the same RGB node, but connecting each node the a duplicate of the same rgb node seems to resolve the problem (see screenshots attached)

Sample file:

For the records the issue also happens in 2.79.

Original description of error

In the attached .blend are 9 cameras set up with sterescopy. The compositor separates and saves each camera output to a different directory.
For some reason, with every file output from a certain camera there's another file output from a different camera (lets call it parasite camera) , only this one is black with no data (see attached screenshot).
a few charasteristics:

• The parasite camera output is added to every output of the other cameras, but not to its own
• Rendering again changes the parasite camera to a different one (in the screenshot it was 'Cam006', in other renders it was a different one)
• It's not clear how the parasite camera is "chosen", it isn't selected or active, and it's not the scene's camera
• There's no file output in the compositor that suggests this output