TurboTax tilde file disappeared

It was my understanding that TurboTax files that have a tilde (~) at the beginning of the file name are now permanent backup files that are not automatically deleted anymore.  However, one of my TT tilde files has just disappeared.

 

The file that vanished is the file that has a double tilde (~~) in the file name.  It has a double tilde because it was automatically created by TT as a backup to my single tilde file. This single tilde file was an automatic backup to the original TT file that had no tilde, which became corrupted and unusable.

 

My questions:

  1. What happened to the double tilde file that disappeared?
  2. What will happen to the single tilde file that is now my primary -- and only -- TT tax file?  Will it also disappear the next time I close the file?
  3. If these tilde files are in fact temporary files:
    1. Can I convert them to permanent file by renaming the file to remove the tilde character?  This has the advantage of not needing to open and close the file.  Or…
    2. Must I open the tilde file and then do a Save As to a new file name?  I prefer not to do this because that will also change the file’s Modified date, which I use to keep track of when files were finalized. 

Note that I didn’t change these tilde file names earlier because I read a post that said changing the default TT file name caused problems for the poster.

 

Thanks.