Unable to make payroll changes when another IRIS user in making changes

Morning, we have had an instance this morning whereby one PM has been in the payroll making changes to the payroll and the client called another PM and asked for the payroll to be submitted for approval. It allowed the second PM to do this, stopped the other PM making any further changes. I think if there are 2 people making changes, one shouldnt be able to submit for approval whilst the other is still making changes.