[Dovecot] dsync strange duplicate directories

Hello, i'm testing whether dsync will help me in setting up a redundant master - master imap setup and experience this:

1. Master 1 dovecot is running, master 2 dovecot is down
2. I use rsync to create an exact copy of the master 1 maildir on master 2
3. I start up master 2 dovecot
4. I do a dsync on master 2: dsync -D -u test@example.com mirror ssh root@master1 dsync -D -u test@example.com

Now what i see is this: Each mail directory is duplicated on master 1 and master 2 to a directory name with some MD5 hash value (as it seems)

e.g. before dsync: ls -a /home/vmail/example.com/test/Maildir cur new .Drafts .Junk .Sent ...

after dsync: ls -a /home/vmail/example.com/test/Maildir cur new .Drafts .Drafts_af61060f6f9fcb4efc0a00002691362e .Junk .Junk_b261060f6f9fcb4efc0a00002691362e .Sent .Sent_b261060f6f9fcb4efc0a00002691362e ...

The new directories contain the same files as the original directories. What am i doing wrong? Thanks for the help Frank