The matter is very simple here

If you are allocated a non clinical md/ms via the all india quota or state quota seat,you have 2 choices -

Either you could not seek admission to the institution allotted to you in the md/ms counselling at the all india or state quota within 2 days of such allotment - in which case you non clinical md/ms will be forfeited

Or you could get admitted to the institute allotted to you viaa MD or MS  and participate in the DNB counselling date after and if you are allotted the better seat then give resignation or get leave certificate from the head of the institution of your previous allotted institute where you was pursuing MD or  course and give forfeiture amount of money as laid down by the institution or the university to free yourself from the bindings of that institute and join the clinical seat allotted to you via DNB