SpiderOak ONE retains historical versions of all your backed up files. To find and download one, open the Manage tab in the ONE desktop application on your computer and navigate to the file you are interested in. If the file has changed since you first started backing it up, then you will notice a number in parentheses following the file name. This number is how many historical versions SpiderOak has of that file.
Select the file, and the history column will unfold from the right. In that column, you will see a list of all versions of that file, along with the date and time each was saved. Select the version you want, press the Download button, and download it as you would any other file in your SpiderOak account.