If you run 35 passes with CCleaner and wipe free space, then if it finishes and you run it again back to back, does it mean you have wiped it 70 times or does it ignore what has been wiped and look for new stuff?
The passes won't double if you run it the way you've mentioned above. Also, the developers created a page with details regarding the Wipe Space function found in the CCleaner application.
Here is the page: https://www.piriform.com/docs/ccleaner/using-ccleaner/wiping-free-disk-space
According to the page, there are the limitations regarding the Wipe Free Space: