This is a limitation of the Macintosh environment sitting on top of A/UX.
The Macintosh limits filenames to 31 characters, so there's no way for
Retrospect to deal with this. It's not a Retrospect (or AUX, for that
matter) problem, but simply a place where the emulation isn't perfect.
You will find, if you look at that directory in the Finder, that the
filenames aren't complete (view with Small Icons, it's easiest to see). If
you attempt to move these files via the finder, they are created in the
final location with a truncated filename.
This is documented, by the way, in Dantz's manual "Retrospect A/UX backup
for the Apple Workgroup Server 95" on page 30 under troubleshooting.
The workaround is to rename these files so that their filenames match the
Macintosh naming restrictions (31 characters). This should be a rare case,
and the Retrospect log makes it easy to track them down. An alternative
would be to back them up exclusively in the UNIX environment with tar, cpio
or one of the other backup utilities.