Do You Have More Than One Twitter Identity?

Just had a thought (not a regular occurrence).

There is huge coverage in the mainstream UK press about Twitter and it has seen an explosion in user growth recently, just take a look at some of the UK celebs and their follower numbers:-

@stephenfry – Stephen Fry – 204,139
@wossy – Jonathan Ross – 107,107
@schofe – Phillip Schofield – 75,033
@chrisdjmoyles – Chris Moyles – 66,196
@fearnecotton – Fearne Cotton – 29,904

So my question is this, while there are obviously huge numbers of fans joining twitter, how many are actually active and how many people have more than one identity?

For example, I have @kevindixie @fuelmyblog (website feeds, was me) @thedailydust (website feeds) @theblogbus (future project) @FMBupdates (feeds only) – So if I have six names, does that count as six users?

Do you have more than one identity on twitter, if so how many and do you think each person should be restricted to one username like facebook?