I am trying to replace two or more occurences of (like ) tags together with two
Probably not the answer you want to hear, but it is general wisdom that you should not attempt to parse XML/HTML with regular expressions. So many things can go wrong -- it's a much better idea to use a parsing library specifically meant for such data, which will also completely bypass the issue you're having.
Take a look at JAXB if you are certain your HTML is well-formed XML, or if the HTML is likely to be messy and incompliant (like most real-world HTML) you should try something like TagSoup.