Practice and Contradiction

A young child need not have taken a course in Formal Logic to be stymied if told to both do and tnot do one and the same thing, at one and the same time.  Thus, it is unclear which of the following is more fundamental: 1. Not-(A and not-A), or 2. One cannot simultaneously both do and not do A.  In other words, it is not certain that there is not a Practical Principle of Contradiction that is independent of, if not prior to, what, for millennia, has been accepted as a, if not the, cardinal law of Pure Theoretical Reason.  Indeed, perhaps #1 is derived from #2 just as a Proposition is abstracted from a Proposal, and an Event from a Doing.  Now, if Kant is aware of such an autonomous Practical Principle, his examples in the Groundwork do not effectively illustrate it.