New overlapping courses As departments grow, they tend to hire people in the same area of research. And different people from different communities call things differently. For example, people in Statistics may call it "Statistical learning", while others "Pattern recognition". If several departments or people within the same department propose courses with similar content but different names and no one wants to change, what can be done at this point? Offer 2 courses but allow students to take only 1? Offer 2 courses and try to minimize the overlap? A senior faculty, chair, or dean should decide on 1 course only? Other ideas?
If it is between 2 possible courses, its better to check what is different and what is the same, then join what it is the same and if there are not that many differences then add them all in the same course, if there are many, then you can either give one course with extra set of classes for each course (which is a bit of an administrative nightmare), or you can give 2 courses with shared classes of those that are the same.

As an example, in my university there are 2 extremely similar careers. 1 in the Licencee in Informatic sciences, and the other is the Licencee in Enginery of Informatic sciences. They are basically the same in most courses with same professors teaching in both, however, the first one has administration courses and the second has instead physics and chemistry. The other difference is that one has 1 semester of probability and another of statistics, and the other has both probability and statistics on the same semester. Who decides this? the direction of the school and the heads of careers/departments. they revise and update curriculum plans and then send them for approval/registration to the national education department, which might not be needed in your case.

My suggestion regarding the courses is in sum to check what is different between the proposed courses and see if it's worth A)to make them separate, B)Mash them together into 1 course, or C) Make 1 course with 'optional' extra classes needed for the student to Attain the credits to the different subjects.

Who needs to be consulted? All your stake-holders, meaning all the professors, chairs and  such that would participate in the definition of the curricula.