I think it would be awesome if Recuva had the option to warn a user if they are attempting to save a file back to the same partition of a drive, or back to the same drive, of the dangers of this. Perhaps something similar to:
"Recuva noticed you are trying to save recovered files back to the same drive you are attempting to recover them from. This is not recommended & may cause data you are trying to recover to be overwritten. Do you wish to select another drive to recover the files to?"
Or, an even simpler statement, if you know how to effectively word it shorter...
"Same drive saving not recommended. Select another drive?"
* But include the option to hide that warning message, just like in CCleaner.