Some types of special leave need double validation before it gets approved. It has to be configured on the Leave Types. As soon as the leave is applied by the employee, it asks for approval twice.
Let's configure the Leave Types to Compensatory Days to have double validation:
Now, when an employee requests for a leave, it will not be approved until it is approved by a second manager:
After having the first approval, the VALIDATE button will appear, and leave will be waiting for the SECOND APPROVAL stage.