Havdalah

Question

Is a person allowed to make havdalah more than once for people who haven't heard it yet? I was in a shul tonight (Mosa'ei shabbat) and after arvit they were asking if anyone could say havdalah. I asked why anyone couldn't, and was told that you shouldn't if you're going to say it again at home. Why would this be, and why would it be stricter than kiddush, which I know I can say over and over? Thank you, Sam