During a live persistent session I noticed the -old files residing in /var/cache/debconf/ bear older creation dates.
The various .exclude lists already include pattern
/var/cache/debconf/*-old
which suggests that rsync is ignoring/discarding any"...asterisk dash..." patterns.

related note:
These 15Mb+ files are regenerated each time apt-update is performed, so this pattern can be listed in persist-save.exclude
/var/cache/apt-show-versions/*

My experience with anything with anything ending with .old after a dist-upgrade.

Though live persistence is not how I roll skidoo.

Anyways. .old is just a backup of original so I can restore original settings if new dist-upgrade file breaks something on my install.

That is just my experience talking. .old = .backup

If I am off base and missing your point entirely.

Then never mind.

rok, in this case, the filenames literally end with the chracters"-old"
and the issue is that rsync seems to choke/ignore patterns containing"/*-old" when it parses the excludes lists.

Found out the problem wasn't specific to any existing pattern.
For use with overlayfs+rsync, ALL pattern pathnames need to be prefixed with /upper/ in order to match.
BitJam has released script(s) updated to address this.