2 mailbox in the same outlook 2003 windows

I would like to manage 2 mailbox in the same outlook 2003 windows (one
profil, one account).

I configured in AD the right user and it works fine. I open a session on
account A, run outlook and see the mailbox A and B in the same outlook
windows. BUT, when I send a mail from account A for/as account B all the
mail begin in the header with the information

FROM A as B (something like this ?)
TO C

Is it possible to clean the from line (FROM A, not FROM A as B) ?

Regard

Alfred