How do I add an extra user title field?

[corsacant]

Hi,
I'm looking to add an extra user title field to my forums.
At the moment I have just the standard user title field. My problem is that I have premium members who are also staff of the site. I would like for 2 user title fields, one that is editable as normal for the user, and one that is only editable for me (the admin).

Here is my current layout:


And this is how I would like it:


Any help would be greatly appreciated.
Thanks.