Yes but you wouldn't do that, being the disciplined and fair-minded player you are, now would you?
It's there to give you the option to decorate your crew for their performance as you see fit, without the constraints of the SH3 medal rules. If I remember right, the entire crew of Hardegen's U-123 got a Knights Cross when they returned from their first Drumbeat patrol. Even if you were as successful in-game as U-123 was in real life, you wouldn't be able to do that in SH3.