Hello aspirant

There is no such as quota in medical College. Either you are twins or siblings doesn't matter.

Reservation or quota are mainly based on caste, PWD, central pool, now from last year some seats for covid warriors (doctor, nurse, health workers, police etc) child who died  during duty.

You will both have to score good marks and admission will happen according to your marks and ranks.

You can use NEET UG college predictor tool for knowing your chances in MBBS, BDS college

https://medicine.careers360.com/neet-college-predictor

All the best