I'm not an authorized personnel from the Department of Education
for the State of Maharastra :) But it should be possible to do that.
If its just to change the college allotment, then I think its bit of a waste.
However, the institutional resources and peer group calibre would affect
you in a positive way ... if you are up to taking and looking out for
challenges :) So, if you feel you can do better a second time, just go for it.
I don't think anybody would care to ask you about your first attempt or it
is necessary for you to mention it later as well.
But there's ton's of good books and material that you could help yourself
with, and there's internet as well. So you can stick to your current
institution as well.
If you are interested in changing your stream to Medicine or something
different altogether then there's no stopping you.
Presuming that you have been admitted to an engineering insitution,
I hope you haven't parted with a significant donation to the institution.
If so, you should really think about doing anything drastic. Although, just
reappearing for another MHT-CET wouldn't hurt you.
So, hopefully you'd just have to incur the additional expenses for the
MHT-CET exam fees apart from your annual engineering college admission
Hope this helps.