Is it necessary for an employee that is wearing a face shield, to also wear a cloth mask underneath?

The use of either one or both depends on the protection desired as informed by the risk assessment which looked at various activities within the workplace. The shield is to protect the worker from droplets and splatter and also protects the eyes, however a surgical mask is designed to contain inhaled droplets from being expelled into the environment by the wearer/user. A cloth mask is not considered as a PPE as it does not have a protective factor and merely aids in reducing droplet spread.