That is not required. In physical certificates, the unique distinctive numbers are used to identify the number and serial order of shares with the folio number of the holder. Dematerialized shares do not have any distinctive numbers. These shares are fungible, which means that all the holdings of a particular security will be identical and interchangeable. That is what an ISIN is all about. You don’t differentiate between shares held by Ram and the shares held by Shyam. They are all just part of a large pool of shares representing the capital of the company and the DP account holding statement only shows the proportionate ownership that you enjoy in the share capital of the company.
However, you may be interested to know that SEBI is considering the concept of distinctive numbers for demat shares also. It was thought that in a demat environment, this concept of distinctive numbers will not have its relevance as all the shares will be held in the electronic form. But there have been cases of excess demat that have come to light, in absence of distinctive numbers, it was very difficult for depositories, issuers, SEs and even for the regulator to find out who the culprit is. SEBI did consider a new system of dematerialization where ownership of records is kept in electronic form and physical movement of securities is replaced by a book-entry system. However, certain irregularities were observed in this system too, like a problem of securities having been issued in demat form by listed companies in excess of listed capital and transfer of securities by the investors (through off-market) before trading permission was given by the stock exchanges.