I've only had this happen once, but originally I had a save file on Dwarven Moderation without Permadeath due to CTD's. Since I hadn't had any crashes in a fairly long time, I decided to make a Going Rogue + Permadeath character. A few hours in, Save and Quit to switch to my other save to show my friend what the game is like without risking my Permadeath save. And when I went to load it up; It was gone. I hadn't deleted it, and the only save remaining was my Going Rogue one. I'm not too bothered by losing it since it already had died once (and I just ended up showing my friend me being destroyed by Battys, Blobbys and Diggles on a new character, which was far more amusing then it should have been), but it seems like that could become a major problem if it happens to an end-dungeon character.
No, you can have multiple saves. I am not sure about with Permadeath on (Waiting also for CTD's to be cleared up. Been messed up too many times to bother with it for now), as long as the characters name is different for each one. The same name with overwrite a previous save, but different names, will allow multiple saves.
I have yet to have successful multiple saves. I had a character around level 5, decided to start a new character with a different skillset, named it something different, and when I went to reload the first character, it was gone. I am wary of trying this again in fear of losing my current (pretty good) character.
Hmm. It might be because the game didn't recognize it was a non-permadeath character. It might just receive it as "any death, and the perma character is deleted", although it's just speculation. Seems like the most likely cause to me. EDIT: I completely read the post wrong. So ignore me being stupid. I'll just sulk in the corner now.
I had four ongoing saves at one point with different characters so it's definitely not limited to one save in general. Each of my saves has a different name too, (the disappearing was what I'll call "N III" and the Permadeath was "N IV". I thought it might be because the first part is the same, but I've had an "N I" and "N II" at the same time...) so that shouldn't be the issue.
If you've ever looked at the save files, you'll notice that it changes names with spaces in them to just the first word. Or at least something similar to that. My guys have been named "Devon", "Devon II", "Devon III", etc all the way up to the current "Devon XVIII", and the save files are always "Devon.sav" and "bitmap_Devon.sav". Not sure if it chops off where space is, or by some other method, but I think you'll be fine as long as your different characters have different looking names.
@drplote That's actually something I saw and why I thought that was what caused it, but I've had two with the same name followed by I and II at the same time, so I thought it could be another issue. Edit: This latest patch amuses me for some reason. I now believe my save vanished to escape its fate! Smart little Confused Turtle!
