If someone would have obtained two MSc degrees from the same university , how do you put that on a business card?
This will very likely depend on the laws of the country you are in and the norms of the business you are in (does it look complete or pretentious to list all degrees). For example, in Austria you would/could just list all titles (except if you work in an especially "young" company where you would probably not list degrees at all).

Since you seem to emphasize "from the same university", could you mabe explain why this could make a difference to "two master titles from different universities"?