title: How to detect duplicate data?
body: <p>I have got a simple contacts database but I'm having problems with users entering in duplicate data. I have implemented a simple data comparison but unfortunately the duplicated data that is being entered is not exactly the same. For example, names are incorrectly spelled or one person will put in 'Bill Smith' and another will put in 'William Smith' for the same person.</p>
  
  <p>So is there some sort of algorithm that can give a percentage for how similar an entry is to another?</p>