What's in a name?

There's been some recent news items on the ease with which people can change their name which seems to throw into disarray all sorts of things such as (always a hot topic) tracking paedophiles. Having had a little think about this it's left me baffled as to how any tracking systems or databases could have worked even if people couldn't change their names. Just thinking about myself with a fairly common name (I am constantly getting mail for my namesake in another part of my company) does this mean I could have been confused with anyone else with the same name on the paedophile register? Surely people must be tracked by something other than just their name, like a social security number or something? In which case should it matter how easy it is to change a name as long as it's not possible to get a new social security number to go with it?