(1) Without prejudice to the provisions of section 21 of the General Clauses Act, 1897 (10 of 1897), a detention order may, at any time, be revoked or modified--
         (a) notwithstanding that the order has been made by an officer of a State Government, by that State Government or by the Central Government;
         (b) notwithstanding that the order has been made by an officer of the Central Government or by a State Government, by the Central Government.
         (2) The revocation of a detention order shall not bar the making of another detention order under section 3 against the same person.