Under Criminal Law, informant means complainant.
154. Information in cognizable cases.
(1) Every information relating to the commission of a cognizable offence, if given orally to an officer in charge of a police station, shall be reduced to writing by him or under his direction, and be read over to the informant; and every such information, whether given in writing or reduced to writing as aforesaid, shall be signed by the person giving it, and the substance thereof shall be entered in a book to be kept by such officer in such form as the State Government may prescribe in this behalf.
(2) A copy of the information as recorded under sub-section (1) shall be given forthwith, free of cost, to the informant.
(3) Any person, aggrieved by a refusal on the part of an officer in charge of a police station to record the information referred to in sub-section (1) may send the substance of such information, in writing and by post, to the Superintendent of Police concerned who, if satisfied that such information discloses the commission of a cognizable offence, shall either investigate the case himself or direct an investigation to be made by any police officer Subordinate to him, in the manner provided by this Code, and such officer shall have all the powers of an officer in charge of the police station in relation to that offence.
Criminal Law says that there can not be two informants and there cannot be two FIR for the same offence. However criminal Law says that it is not necessary that the informant has to be the victim. Take an example of rape with a minor girl. In this, either father or mother of the prosecutrix is a informant and not the victim.