Child theme is WordPress feature. In c5 : copy and paste the folder in same hierarchy and thats it. Do this only if your new theme is really really difference structure from to original theme - and keep areas names.
Otherwise use CSS to get endlees design for the same markup:
http://www.csszengarden.com/
Or Style customization theme feature:
http://documentation.concrete5.org/developers/designing-for-concret...
And blocks templates:
https://www.concrete5.org/documentation/general-topics/custom-templa...

If you still want to dupliucate your theme:
application/themes/fluke/
application/themes/fluke-ver2/

Inside "application/themes/fluke-ver2/" Change the description.txt file:
fluke-ver2
this is my new fluke template description

Change the thumbnail if you want.

---- Some tuturials ---
converting-an-html-template-to-a-concrete5-theme:
http://documentation.concrete5.org/developers/designing-for-concret...

Themes:
http://documentation.concrete5.org/editors/dashboard/pages-and-them...

Basics consepts:
http://documentation.concrete5.org/developers/concepts...

Hi siton... Thanks for quick reply..!
Is it required to keep themes in app/themes folder only..?
Now my current theme path is : app/theme/fluke
And I want to create new theme having dir structure:app/micro/fluke/v2 and this v2 folder will contain all themes files like default.php, veiw.php, png,txt etc....
Is it possible..?

No. This is how the system works, why to change this? Its very nice and clean structure (look at elemental theme for example).

In all CMS you find the templates in root theme folder. You can use :
<?php $view->inc('elements/nav.php'); ?>
And create any folder structure you wants.
http://documentation.concrete5.org/developers/designing-for-concret...

You also can choose specific theme to specific page - use the GEAR icon in edit page mode and "design" label - i never use this feature.