I'm not sure If there is a term for recording 1 input at 2 different levels, so I'll refer to it as dual audio.
Recording dual audio has saved me countless times. Not just as a backup(if it's on another device) but for capturing one input higher and one lower. Depending on the dialogue if you have someone going from quiet to loud quickly, sometimes you can still clip the audio while riding the gain. So on a dual setup keep one line at operating level(what you're monitoring) and one at maybe -5dB. With both recording from the same source.
This way even if you blow it on the main input you have a backup that's slightly lower and hopefully didn't clip.