So, one is harm, the other just a rule..?
I have had to put 3 cats down in my life, all were terminally ill and in distress. It was obvious that I had a duty, however difficult. But I cannot get over the guilt of killing my pets who trusted me unconditionally. It is not rational, but then feelings rarely are, which I why I do not think you can divide these ones up so neatly.
It is true I feel shame if I break my own rules, if I feel I dishonour myself, if you will. But even more if that causes harm.
I still think it depends on the situation.