Colleges in Nagpur

No, it's legally not valid. Students should not be allowed to undertake two regular degrees at the same time. On January 19, the University Grants Commission (UGC) said that its consultations regarding allowing students to pursue two degrees courses simultaneously have not received a positive response so far. According to a report in Press Trust of India (PTI), UGC said in a post, "It had sought the comments of statutory councils but the responses so far do not endorse the idea of allowing students to pursue two degrees simultaneously".
According to the notice signed by UGC Secretary, Jaspal S Sandhu said, "Therefore, the Universities shall conduct their programmes in accordance with the first degree and Master's degree Regulations, 2003 prescribed by the UGC and also follow the norms and parameters prescribed by the Statutory Council concerned, wherever relevant".
In 2013, an expert committee of the UGC had recommended that students enrolled in a regular degree course should be allowed to pursue an additional degree simultaneously under open or distance education mode from the same or different university.

Hello Vaishnavi,
Yes, indeed. You can definitely seek admission in GMC based on your NEET ranking. However, this year DMER is not the agency. I am attaching a link through which you can register. This year's Health & Science Admission Process is started and also, there are some changes, now DMER is no more a counselling authority, those who are interested in Health Science courses such as MBBS /BDS/BAMS/BUMS /BHMS/BPTh /BO&P/Both/BASL /B.Sc Nursing and appeared for *NEET UG 2019* must register at Setup Assisted Application Registration (SAAR) & upload required documents & also verify your documents with your the nearest Setup centre:
https://www.maha2019cap.org/Student/Registration

Both, degree and Diploma are types of recognition conferred on a person on the successful completion of an educational course. However, there are a lot of differences between the two and they aren't interchangeable. To understand the difference between a degree and a Diploma, we first need to know what a university is, what AICTE is, and the role of the University Grants Commission (UGC) in India.
University
A university is an institution of higher education and research, which grants academic degrees for a number of courses. UGC stands for the University Grants Commission. The UGC was established in November 1956 as a statutory body of the Government of India for the coordination, determination, and maintenance of standards of university education in India. All cases pertaining to the allocation of grants-in-aid from public funds to the Central Universities and other Universities and Institutions of higher learning might be referred to the University Grants Commission.
AICTE
What UGC is to universities, the All India Council for Technical Education (AICTE) is to private institutes that impart technical education. The body works towards qualitative improvement of technical education, and towards implementation and proper maintenance of norms and standards in a technical education system.
What is a Degree?
The duration of a degree course is usually 3 to 4 years and the emphasis is on academics. For example, B.Com (H) is a 3-year degree course that teaches students subjects like accountancy, economics, and business studies; B.Tech is a 4-year degree course that teaches subjects like physics, chemistry and math, and includes the subject one plans to major in, an MBBS is a 5 and 1/2-year long degree that teaches the general aspects of medicine.
Who Confers the Degree
Only a university can confer a degree. To pursue higher education, only a degree from a UGC-approved university is accepted. AICTE-approved private institutes are affiliated to UGC-approved universities. In case a person graduates from an AICTE approved private institute affiliated to a UGC approved university, he still gets the degree of the university. Example: There are many AICTE approved private colleges under Guru Gobind Singh Indraprastha University, but after the completion of the course the student does not get a degree of the institute, he gets a degree of the university in this case, Guru Gobind Singh Indraparastha University.