How will CL know that an identical ad on CL and another site wasn't scraped, but just double posted by the author? Do you really think CL is just going to politely ask?
Do you really think CL is just going to politely ask?
They can politely ask the poster and see if they posted it elsewhere. If yes, nothing else needs to be done. If no, they are probably going to find out the extent the external website has gone to.