claim of HRA and Housing interest both simultenously

yes it is possible

yes

My client has two house properties one at Kolkata and other at Noida. He resides at Kolkata for employment purpose and stays in a rented house. The Kolkata flat is rented out and the Noida flat is vacant. He gets HRA from his employer.

The issue is whether we can claim exemption from HRA as per the Act, showing Noida flat as self occupied as per the provision of section 23(2)(b) and declaring the Income received from the let out property at kolkata? 

yes it is possible you can claim both simultaneously