In AP EAPCET counseling, in case you are allotted a seat in the 2nd round counseling then your seat would be automatically canceled in the 1st round only on reporting to the 2nd round seat.

This is how it goes:
Your 1st round seat will still be valid in case you do not do anything about it (i.e.  do not report or pay the 2nd round seat).

Assuming you accept the 2nd round seat (which would require payment of the fee/reporting), The 1st round seat will be cancelled, no further action is required.

Thus, the cancelation will depend on what you do. When you like your 1st round  seat, you need not bother about the 2nd around allotment.