I've had it happen three times, now. Has anyone else seen this?
I'll be developing away with five or six files open in VS/Mac, when the tab for file-c now contains the contents of file-b, and the tab title changes so that file-b is now open twice. If you're not wildly observant, you can compile, causing file-b's contents to be written to file-c, and your original file contents are lost. Forever. You'll know it has happened when you get several dozen compiler errors that something is defined twice. The last time I was lucky enough to notice that the same file was open in two tabs and could exit without saving, so that I only lost my last few edits.
So far I haven't figured out a pattern to when it happens in order to reproduce it, so I'm not going to report it yet. But if you've had this happen to you, and have any clues as to what might be causing it, please reply. It's an incredibly painful bug, and they'll need more information than I currently have to have a prayer of fixing it.