Regarding Marriage Registration

My sister and her lover working in Chennai. Her lover is from Odissa. Our both family are fine with their marriage, which is planned in Odissa and his family members will register their marriage in Odissa. Can we register in Chennai also, or it be considered as duplicate registration. If they register in Odissa, we need to get any affidavit here. My mom asking to register in Chennai, but his family members is not ok for that, as marriage occurs in Odissa they planning to register there.