Do I need another GST Number - Another Business

if there is different business so you need to take 

in case of similar business vertical you can continue with same number within same state

No need to take new GSTIN in same state  if it's same activity or different activity...

Except your will...

however you can add branch in existing gst registration 

Not required to take fresh registration. 

welconme 

No need to take a seperate registration unless you wish to obtain one to sepretaly consider that business for the purpose of GST. 

incase if you opt to Obtain a seperate GSTIN,

1. You have to maintain records seperately and file seperate returns.

2. Cannot clain ITC one business against the Tax payable of other business. 

3. GST will be levied on supply from one business to the other. 

However it is not compulsory to take a seperate regisration. 

Incase if you maintain the same GSTIN for both business,

1. you have to mention the other business place in additional place of business/ branch

2. delcare one place to be Principal place of business. 

However, in both the cases you cannot opt for composition scheme for one business and the regular schem for the other business. 

Turnover for the purposes of applicability for composition scheme and for other purposes will be calculated on PAN wise Turnover.

Hence, it doesnot make any difference, interm of opting for Composition scheme. 

Its better to have the single GSTIN,as it simplifies accounting, records and returns.