After doing several very specific tests, I now find that apparently Unison does *not* overwrite a file with the same file name in a given path when saving attachments, as I earlier stated with good-faith belief. It appears that it appends a ".1" to the first instance of such a file, prior to any extension. This does not excuse the failure to provide any alert whatsoever that there is already a file with that name, nor does it excuse the egregious absence of standard Mac file requesters in all instances of saving *anything* from *any* part of the program so the user has control over where and under what name a file is saved. There also is the enormously confusing quasi-duplication and/or non-duplication (MIT hasn't figured it out yet) of listings in the Message, Files, and Images panels for some groups since an IMAGE attached to a MESSAGE is a FILE *and* is an IMAGE. So on what basis do these things appear in what panel? Ask the gods, ask yer Magick 8-Ball, but don't ask the documentation. Also don't try to figure out if clearing something in one panel clears it from the others--not in a group you haven't visited in a while in which thousands of files/images/messages--whatEVER--have collected. Not unless you have the rest of your life ahead of you to complete the job by bouncing back and forth between panes. Don't forget when doing it that somehow there can be multiple IMAGES in any given FILE--even though some idiots, like me, actually believe that an image IS a file. Apparently now it's not. Apparently the developers have their own lexicon taped up on their wall, and someday they may let us ALL know what these terms now mean. And, YES, I've bought the program.