with sasl authentication the username in sent twice

[Rob van Dam]

I want to relay my mail from a Trixbox (Centos 5.5) pbx to my password 
protected smtp server. The problem is that acces from the trixbox is 
always denied, because Postfix tries to login with 
username:username:password

I installed Postfix on an Ubuntu distro, and here the relaying works. 
Postfix logs in with username:password

I copied the main.cf from Ubuntu to Trixbox (recompiled sasl_password.db 
en restarted postfix) and the Trixbox still tries to login with 
username:username:password and access is denied. Does anybody has an 
idea how I can get the login right?

Rob