Can an NRI have more than one demat accounts?

Yes, an NRI can have as many demat accounts as he wants.

Usually NRIs open 2 demat accounts; NRE Demat Account and NRO demat Account.

The NRE Demat account is to buy/sell shares on repatriable basis. In case of an NRE Demat Account, both principal and dividend/interest are freely repatriable.

The NRO Demat Account is to buy/sell on the non-repatriable basis or to hold securities which are bought as an Indian resident before becoming an NRI. In the case of NRO Demat Account, the principal is not repatriable. Dividend/interest is repatriable.

Note that NRIs can open multiple of NRE or NRO demat accounts on the same name. But there is an annual maintenance cost (AMC) which customer has to pay irrespective to the use of the demat account.