Hello aspirant!
Hope you are doing well!

In case you have not joined the college allotted to you in NEET 2020 counselling, only then you can participate in the state counselling, but for this you wont be getting back your security money.
In case you join the allotted college, you wont be eligible to exit or surrender from the counselling of NEET 2020 nor be allowed to take part in the further rounds of NEET counselling 2020.

For more information refer to https://medicine.careers360.com/articles/neet-counselling-faqs