[lowbloodsugar]

>I am not sure what should be the appropriate reaction or corrective measure in these situations.

When it happens internally, i.e. I catch someone doing it, then either it is a "first time offense" of the clueless, or it is the act of an unethical person who will be unrepentant. For the clueless, it might be that they undervalue themselves, and therefore undervalue assigning credit. The unethical person, however, understands what they are doing and is simply untrustworthy. They will also likely have a lawyer, because they've done this before. So it can be pricey to get rid of them, but get rid of them you must. They are poison to your team.