MBBS in India is a very demanding course in India itself. You'll have volumes of books to read for your exams and you'll have many surprise tests, for which you'll always have to be on your feet. So, pursuing BPT along with MBBS might not be a good idea as it will affect your MBBS studies adversely.

Moreover, MBBS has a higher value than BPT and if you pursue MBBS full time, you'll be in a much better position.

Hope I have answered your question. All the best!