Lol @ArjenEX
@prashant7526 , if you do have a use case where perhaps a specific node creates a variable with a name over which you have no control, and you actually want it to have a different name…
The only way I know of achieving that is to create a component and have the original variable creation occur inside the component.
You would then replicate that variable using something like Variable Expressions and then on the exit from the component you only let the new variable leave the component (by configuring the Component Output node).
All flow variables created inside a component do not exit the component unless explicitly allowed to leave.
To be honest you have to really want the name to be different. It feels like a lot of effort for a variable name. 
(welcome to the KNIME forum, btw)