How to avoid duplicate entries in desktop system menu?

[Benedikt Meurer]

Christian wrote:
>> PS: Please don't CC me with replies, I'm subscribed to the list. ;-)
> 
> Sorry :-( ... but... I also got every mail from you twice, so I thought
> you whished a CC.

You are explicitly listed in ReplyTo: and so the mail reader will 
include you with replies, e.g. your last mail had this header:

Reply-To: cvjb at cvjb.de, XFCE general discussion list <xfce at xfce.org>

> Bye,
> Christian

greets,
Benedikt