Hello again, I was able to workaround the getmail issue producing dublettes using Sieve-Filter to find and discard dublettes. I was using this Rule-Set (I found somewhere else in Internet). I only have sometimes dublettes now, but not as worse as before (every mail twice!).
> # Track duplicate Mail-Deliveries > require ["duplicate", "imap4flags"]; > if duplicate :header "message-id" { > discard; > stop; > } > > keep; Best regards Gabriel Kaufmann