save_url endpoint to overwrite any files with same names rather copy? (v2)

No, unfortunately the /2/files/save_url endpoint doesn't offer "write mode" options, e.g., to overwrite an existing file at the specified location, like /2/files/upload does. I'll pass this along as a feature request, but I can't promise if or when that might be implemented. 

I'm not sure I understand your other comment though. For context for the feature request, can you elaborate? For instance, as a workaround, you can check if the file already exists first, then delete it if so, and then use save_url to upload the new file at that same location the same way. Would that not work in your use case? Thanks!