Professional Tax Certificate (PTEC) for GST registration

I work in an MNC and also have a side project for which I need to do GST registration. For GST registration I need to provide PTEC certificate. But as I also work in a company, my employer also files professional tax on my behalf in the same state. So do I need to register PTEC again? If not, how do I get PTEC certificate which I can upload on GST portal?