The PATH problem was resolved with the tip of DanB35. Have to make a su- and the Path works perfect.
The IMAP problem was not a problem of the SME server. My kmail has a Menu with an Spam Assistant this assistant works (on my configuration) with bogofilter. At activation of this system the assistant is creating some filters in kmail. These filters caused the problem.
I deleted the filters and no more dupe mails are arriving

Thanks for your patiance
regards
Gobo38