Switched from talking about "unchanged" files to "identical" files.
I found out the hard way that the rclone copy will overwrite newer files.
Looking at posts in the rclone forum, this is a common experience.
The docs for copy have referred to "unchanged" files.
This is ambiguous because it intuitively introduces a sense
of chronology, but chronology is irrelevant.
Rclone only "cares" about difference, not change.