Source: As worded by Indian Railways, Government of India

If the loss of your Confirmed/RAC ticket is reported before the preparation of the Reservation Chart, a duplicate ticket will be issued on collection of the clerkage charge per passenger.

In case of the loss of your confirmed ticket is reported after preparation of the Reservation Chart a duplicate ticket will be issued on collection of 50% of the fare. No duplicate ticket will be prepared after preparation of Reservation Chart in case of RAC tickets.