The only time a person on active duty can receive money from VA and the military for the same course is under the "top-up" provisions. These provisions apply only to persons eligible for Montgomery GI Bill (MGIB) chapter 30, benefits,
Most service departments did not have the budget to begin paying 100% tuition assistance, so Congress allowed MGIB eligible individuals to access their MGBI benefits to reach up to 100% tuition reimbursement (top-off their tuition assistance benefit). Thus, if the military provides tuition assistance that equals 50% of the cost of a course a MGIB, eligible veterans may use their MGIB benefits for the remaining 50%. This is the only time someone on active duty can receive money from VA and the military for the same course.
https://www.tsc.fl.edu/student-life/veterans-affairs/guidance-for-choosing-gi-bill-programs/