Is it called reusability?

I was recently going through the internet booking facilities of the airlines under the new formed National Aviation Company Of India Limited. Something odd stopped me at the Air-India Express site, the low cost carrier of Air India. When I took a closer look, its side bar resembled the side bar of some other airline I have seen already. I started checking the sites of other airlines . As I suspected it looked exactly the same as the side bar once used by Air Deccan.

I explored both sites a bit more to understand, how both the sites got the same template. The link between the two is InterGlobe Technologies, which maintains the Air India Express e-Ticketing System and maintained the Air Deccan's e-Ticketing system till February 2007. InterGlobe maintained the Air Deccan system from 2003 till early 2007. Air Deccan terminated the service on the grounds of deficiency of service and migrated to Radixx system when InterGlobe launched its own airline Indigo. Now InterGlobe and Air Deccan are locked in a legal battle over the termination of contract and payment disputes.

Air Deccan has masked its side bar and now redirects to the booksecure.net platform of Radixx. Open the images to have a better clarity.

Air India Express site has exactly the same side bar and menu bar templates used by Air Deccan. Is it called reusability? I wonder how Air India has approved this design reuse by InterGlobe.
No wonder, InterGlobe stills calls Air Deccan as its client in its site 6 months after snapping up ties.