On occasion backup models show up in folder and regular models disappear.
When I open the backup file it is untitled. At other times backups show up
with regular models. I am concerned both are going to disappear one day.
Any thoughts?
Sounds like a Windows Explorer issue more than a Rhino one. Do you have file extensions turned off?
You may want to check or uncheck Create Backup in your file options in Rhino, depending on your choice for this.
When in doubt, “turn it off and turn it back on again” 
Turning off the backup option seems to have worked. I auto backup anyway.
Thanks!