When the GST is newly implemented, then only one registration are allowed in one state but also allowed in vertical business (means for different business in same state under same PAN) but Now vertical business defination is drop out from scope of GST but now you are free to take no. of registration in one state but keep in Mind for each registration you are considered as separate Person, you have to file separate GSTR 3b and GSTR 1 and so on.
soo better option is if required then only take multiple registration otherwise go with one registration otherwise it will increase your legal work load.
@ Mr.Vijay prakash its not allowed earlier but now there is no restriction on multiple registration but it's create huge GST compliance Soo advisable if requirment, then only go with multiple registration