Chat with multiple users without opening new tabs from browser

I want to open multiple user chat boxes in same page without opening a new tab, can this be achieved using Rocket chat?

Do you mean with multiple user chatboxes that you want to chat with multiple users privately in the same chatbox at the same time? If so, yes that is a standard option in RC. You can chat one on one between you and multiple users. Every user is then listed as a direct message channel which you can click on. This will open the private chatbox in the same window. So no extra tabs or windows.