Source: As worded by Indian Railways, Government of India

If your luggage marginally exceeds the Free Allowance, you will be charged at normal rates. Above marginal allowance penalty will be charged, if detected. Make sure to book your excess baggage in the Luggage Office, pay the prescribed charges and get your tickets endorsed by cross-referencing the luggage ticket details, before commencing your journey.

Please note that Free Allowance is not admissible for articles such as scooters, cycles etc.