Gst registration for same prorietor but two diff. business

Is two different GSTIN number reqd. for two businesses run by the same proprietor in two different names but same state? The first is a retail outlet and second is sub broker services. The first one is already registered under GST and the second one yet to be registered. Shall we go for a new registration or amend or add services in present  GSTIN.

Please advice.