Ok this topic came up a long time back as well.
The double bogey mail wheels were specially designed to allow operations into airports like Indore, Jhansi and almost all airports in the North-East where runways are pretty rough. Apparently, the B737-200's that IC operates never had this problem. (Dont ask me why!)
However, IC was the only airline to operate these uniquely configured A320s, and procuring spares was becoming a major problem. So IC started replacing the double-bogey main wheels with conventional landing gear. Perhaps that conversion is now complete.
Another thing that i have seen is that some A320's have some kind of plate fitted to the front landing gear. I havent seen this modification on any other A320's, and many in the IC fleet did not have this either. I was told this was to prevent gravel ingestion!