Urgent:can marks once alloted be reduced later?

yes it can be reduced

No that would not make any sense isn't it? There is no rule for or against reduction of marks in my knowledge. But in any case you are just asking for a copy of your answer sheet. If you choose to get it reverified then I am not sure. In that case also I have never seen an example of reduction of marks.

in revarification marks can be reduced

ICAI will show you the answersheet ( if possible ) , with the marks matching to your Result !