you cannot say mumbai has 2 , so kolkata also should have 2 ... conditions are different .... kolkata has ER which is such a small zone which actually should not exist ... but due to politics kolkata has been given 2 zones .... actually i alraedy said before all divisions that come under wets bengal should be in ER .and the remaining divisions of Jharkhand along with BBS , Sambalpur should come in SER