Yes,  your second round seat will be retained even if you don't get a new college allowed in the third round of counselling. If at all you get a seat in third round of counseling then your present second round seat is lost. Else,, the seat which was previously allotted to you will be there  with you.

Hey Chandan,

If you alloted Bharath in first round/phase and you want  to go with next round then if your rank is enough then you will be alloted other seat if not then then you will again alloted the same seat. You will not loss your seat untill you will not alloted.