If the boss has a pattern of unjust behaviors, then you can forgive for the pattern itself rather than take each incident one at a time. If there are only two incidents as you describe, I would recommend forgiving the boss two times, for each discrete incident. It will be less complicated if you separate the two. Yet, if these two are part of a pattern, it may be better to forgive for the pattern so you do not have to forgive the boss 10 or 20 or 50 times.
For additional information, see Learning to Forgive Others.