@ Author,
1. If a Hindu marriage is performed with all the essential ceremonies the marriage is valid. If all the essential ceremonies are not performed, Registration of the marriage does not itself make the marriage valid. There are two essential ceremonies that must be performed i.e. saptapadi and invocation before the fire or if there is custom peculiar to party the same must be performed.
2. The second marriage if registered after taking proper divorce from previous marriage which you say you have taken MCD in previous marriage then your second marriage is a valid marriage. But, the second marriage Registration is not a valid Registration of Marriage as one of the Statements given to Register the marriage is believed to be a False Statement made knowing well it to be untrue as per S. 199 of IPC.
3. If your second husband challenges the Registration of Marriage then only thing that you will be subject to provided such challenge if proved is punishment in accordance with above Law and may lead to divorce.
4. However, if Registration of marriage is challenged then there is a procedure called ‘plea bargaining’ if proved the Statement given by one party during Registration of Marriage was intentional false statement which comes out only with leading evidences - cross examination of you and not summarily. The moment you declare upon facing such challenge that such and such Statement believed to be False was unintentional and unintended and admit guilt and seek plea bargaining, lesser punishment and/or summary cost may be given which are all matter of trial in a Court of Law r/w only if your second husband after knowing all these would take you to Court???.