Yes you can. Firstly you have to add second account holder in your primary hdfc savings account which converts it's status from single to joint. After that kindly submit debit card request for 2nd account holder which results in two debit cards in your primary hdfc savings account i.e. platinum esdc for 1st holder & millennia DC for 2nd holder OR vice-versa.
But u will not get 750+750 in ur both cards bcz hdfc has a rule if u used same varient cards in a single same ac number shall be entitled capped 750 cashback only ..may be I am wrong expert told this better I haven't used this 😅
I paid SC bill of 50000 using SBI Virtual Debit card. I received Actual 2 points per 200. So Overall 500RP=Rs.125 worth and got also additional bonus 500RP which value is Rs.125. So Overall 0.5% for 50k bill