Cannot update RequisitionGroups

Now it looks okay. Proper error message is thrown: "Requisition group program schedules within a requisition group must have unique programs".

It is thrown when updating any RequisitionGroup even without modifications and I believe you are correct that it tries to re-create schedules and runs into some issues believing it already exists.

When adding the validation, remember that there MAY be requisition group program schedules with the same programs - they just cannot be assigned to requisition group in a way that would violate the facility-program-schedule uniqueness. eg. I can have monthly and quarterly schedule for the essential meds program and I can have separate requisitions groups - one following the monthly schedule and another the quarterly schedule which is OK, but one facility cannot belong to the two of them at the same time.

I believe so, is that what you are doing?

So, the error is being thrown when we want to have two requisition group type schedules with the same program (which has a unique constraint), or when trying to remove and insert a program schedule with the same program at a time. The second one is probably some transaction-scope problem. For the first issue, we should only add validation for that, right?

most likely.