I have been asked to explain that two different formulation which Kant gives of universalizability test and how they might lead to different evaluations of a single action based on particular maxim. However, I am having hard time to find these two formulation. So what are these formulations and in which book Kant mentioned about it?
As this is a homework question, I will only give hints without giving you the pages or quotes as extracting the forms would be trivial then.
You mentioned the Critique of Practical Reason in your comment. That is the deciding hint. There is the fundamtental law of morals more at the beginning and then a type of it, as he says, later on which he says to be needed because we would have no scheme to apply the former directly, but would implicitly always apply the latter. This is a point where he directly contradicts GMM, by the way.
Because the latter has a specific notion of law, it is worth discussing wether it has the same mode of universalization.