Investigating: "Unchanged" disposition selects "default"

[webdevpythonicenthusiast]

In the Disposition dropdown, clicking "Unchanged" appears to select "Default" (which is the default selected option). All other disposition options (e.g., "Original," "Remove," etc.) are selectable and function correctly.

I'm trying to understand the intended behavior/functionality of the "Default" disposition. Is there any processing involved that might modify the stream data (even if not full re-encoding)? Or is it possible that "Default" internally uses the same stream handling logic as "Unchanged"? If so, that might explain why selecting "Unchanged" doesn't visually change the selection from "Default" (just what I thought, I'm not a developer).

As a workaround, I'm wondering if the "Original" disposition option can reliably substitute "Unchanged" in cases where the source file does not contain duplicate streams.

OS: Windows 10
App Version: v3.64.0