It is possible to have a glass coating on top of ceramic coating, but it is not a common practice. The purpose of having a ceramic coating is to provide protection to the paint on your car, while a glass coating provides a glossy, hydrophobic finish. It is possible to have both, but it is not necessary as ceramic coating already provides a durable layer of protection. Additionally, having both coatings may result in added maintenance costs and potential compatibility issues. Ultimately, the choice to have both coatings will depend on personal preference and the level of protection desired.