You are probably on the right track. AFAIK, most Indian ISP's have city or state level blocks of IPs. Ultra big cities like Mumbai, Delhi, Bangalore itself has several blocks. So theoretically they could NAT the same IP in different cities or different blocks at the same time, and none the wiser.
> I read, the same ips are being used by ISPS in different parts of the > world with a kind of global nat. > > Also, If you look at the GeoIP lookup data you'll see great swathes were > allocated early on and seemingly never actually used.
