Is it feasible that customer share the same customer ID for both Test and production Keys in same network

Is it feasible that customer share the same customer ID for both Test and production Keys in same network

Problem / Customer Query : 

Is it feasible that customer share the same customer ID for both Test and production Keys same network 

Resolution / Support Comment : 

The customer can share the same customer ID for both Test and production Keys. customer can activate the Test license at Test server and production at production server.