Alternatively, you could name each world on creation, and then prepend that to to the autosave name.
I suggest this because I have just lost several hours of gameplay due to the autosaves being lost.
![Crying or Very Sad :cry:](./images/smilies/icon_cry.gif)
EDIT: I have just thought of another, related, suggestion: make _autosave1 always the most recent, and move the previous _autosave1 to _autosave2, and the previous _autosave2 to _autosave3. _autosave3 is deleted.
My (probably) final suggestion is that you should be able to make worlds save in custom folders, rather that just the default all the time.