Two professors teaching the same course, should they unify their exams? Consider an advanced, specialized, undergrad course. Students are divided into two sections. Each section is taught by a different professor. Both professors follow the same syllabus and textbook (or they are expected to do so to a lrage extent). Do you think they must provide the same exams (i.e. students of each section are given the same exam questions)? Or is it enough for the professors to coordinate and share views, suggestions, etc. and each one can have the freedom to write their own exam for their section? What is the policy in your University?
For advanced courses, I've never had such a policy imposed or used, but it likely happens. For first year courses, it is common for students to have the same exam, but to take it at the same time and be graded together by the (large set of) TAs. First year Calculus, for example. 

But it might be a mistake to give the same exam to different groups at different times or days. It is an invitation to cheat. So, if such a policy were in place, it would seem to be a requirement that a common exam time be made. That may be possible and desirable. Coordination between professors is probably desirable, even if they each use their own questions and deviate a bit. 

This is a US view, where grades overall are normally given for somewhat large ranges of achievement. It isn't desirable if a student can do well in one section but would do poorly in the same course taught by another professor. And even using the same exam is no guarantee of equal results if they are graded by people with different philosophies. 



I'll also note that two such courses may not proceed in lock step for a variety of reasons, such as the teaching skill and/or philosophy of the professor or even differences in the ability of the students in the sections. Even with random selection of students to sections there can be differences and, in some situations, there can be large differences. So, some judgement is needed about how to conduct the exams.