Hi, Thanks for report this issue.
Something must have gone wrong when rebuilding the packages at Debian, because the packages I had built didn't have these differences. I just ran a local rebuild and I still have valid packages, with all the files. It's night-time here so I won't look in depth right now, but https://buildd.debian.org/status/package.php?p=sane-backends&suite=stretch-security should contain possible errors. This could be due to a bug when building the 'all' and 'amd64' packages separately. Cheers! Sylvain
