Hey there

It's good that you want to prepare for banking too along with the preparation of cet. See cet syllabus has quantitative, verbal, and logical reasoning which is also there in sbi po or clerk so if you want you can prepare for it you'll be on a safer side too. Among sbi clerk and sbi bank po the difference is level of questions the number of applicants are huge in both the cases as any graduate can take the exam. So go through past year papers of these exams and decide yourself which exam you want to take.

Hope you understand

Good luck