Hello Buddy! Hope you're doing good.

Yes, you can use only one resevation at all india quota. Well you can try, if you get the opportunity from both of them then it will be good for you. For knowing your college possibility, you can check the link below which might help you

https://medicine.careers360.com/articles/neet-cut-off

And predict your college here

https://medicine.careers360.com/neet-college-predictor?icn=QnA&ici=qna_answer

Hope this will help you.

ALL THE BEST! WORK HARD !!