This is a feature available on most products and would greatly help in knowing not only how many are selected, but avoid errors in selecting more than one person by mistake, if the selected is below the view.
This feature would save the time in both, having to either scan and see that no other employee is selected, or clear and reselect an employee, as well as having to manually and meticulously count numbers of employees selected when there is a need for it. This can be quite frustrating.