Could you copy literally one channel?

With ffmpeg scripts changing the videos in way original content creator couldn't find it, your own voice and changing a little the original script.

You could make it also with your own vids and double the channel benefits

Someone tried this before or is too Risky?

These blackhat tactics have very short life. Even if you make some money, in long term you will still be looking for next earning method. Focus on some stable source of earning like a good whitehat channel.

Very risky in my opinion. Ultimately, your channel will get deleted because of this.