Cheat on the test and you keep the grade but lose the skill. Guess which one the real world asks for.

A grade is a receipt for something you were meant to have gained. Take the receipt without the thing and you are carrying proof of an ability you do not have, which holds up right until somebody needs you to use it. That moment arrives eventually, usually when it counts and there is nothing to copy from. The cost is delayed, not cancelled.

If you are tempted, take the worse mark and keep an honest picture of where you actually are. A low score you understand beats a high one you could not repeat.