When you say they want to duplicate the site entirely, do you mean structure or written content to another language (Hindi). If you target multiple countries then your would be better having landing pages for the relative country and content pages localized and feeding juice to the .com to gain domain authority. This can have value in both mainainability in development costs and allow easier expansion into other markets. Many large sites, Microsoft included would switch content from site.co.in to site.com/in and deliver specific content there and their main content via site.com/content....
If you do create three sites with the same content you may eventually get a duplicate penilty where rankings drop suddenly but you will definitely be splitting the link juice 3 ways. You can easily setup google webmaster tools with the three domains and tell them to give value to the .com if you localize instead of duplicating.