According to Medical Counseling Committee (MCC):-

Candidates are required to join allotted institution/college and complete the admission formalities then only candidate can exercise option to participate in next round(s) and give willingness for Up-gradation at the allotted college, during admission process. For Round 1 as there is Free Exit & Free Entry candidates can resign from their allotted seat in First Round, if he/ she is not satisfied with the allotted seat and can still participate in Round 2 with original User ID & Password of Round 1. Candidates who are allotted a seat in Round 1 but do not join are also eligible to participate in Round 2.