I'm not sure I understand what the actual issue is, Is it just simplay an appearance issue - where a name isn't matching?
Or is there a problem sending or receiving mail? Or some other problem?
If you open the address book on the server (CTRL-O, enter the server name, then open names.nsf) how is your name spelled in the address book?
When you open the entry in the address book, in the User Name field - do you see your names spelled both ways? (Dan Goodwin and Daniel Goodwin)? If so, which is on top?
What is listed in the First Name/Last Name fields?
When you open your mail file, and look at the ACL, how is the name spelled there?
While your mail file is open, and you click 'File -> Application -> Properties - how is your name spelled in the title field of the Properties dialog?