permissions on WebParts via Code (Visual Studio- C#)

Hi all,

I have View with 2 webparts on the view

in the properties for the first webpart I set audience: G1-Group

that mean all users in the G1-Group can see the webpart..

in the properties for the second webpart I set audience: G2-Group

that mean all users in the G2-Group can see the webpart..

But some of users are in BOTH-Groups in G1- & G2-Group

how can I achieve this?

I want that users where are in both groups see only Second Webpart

P.S. I want do that only via Code (Visual Studio- C#)

thanks in advance
BR
Ahmad