ps2pdf: why differences in different instances using unchanged PS source file

[Tom Browder <tom.browder@gmail.com>]

I have been using ps2pdf for many years on a PS source file for a
personalized calendar for my wife. This year I have been cleaning up
my old Perl generating code (in preparation for converting it to Raku
[https://raku.org]) and noticed I am getting a different pdf output
for each run, even when the PS output source file is unchanged!

I have looked at the detailed options for ps2pdf and don't see
anything that stands out to me when using the default settings.

I attempted a comparison of two different pdf outputs by running "od
-c file.pdf" on the two outputs but cannot identify anything familiar
to me about the differences.

My command that runs the actual process is this:

    $ ps2pdf  -dAutoRotatePages=/None  file.ps  file.pdf

I am running on Debian Buster with current updates.

Any suggestions to produce constant output pdf for constant ps input
are appreciated.

Blessings,

-Tom