duplicate inodes after moving messages from Inbox to subfolder

[Marcus Schopen]

Hi,

a kind of node weirdness which makes me a little nervous. My daily
rdiff-backup reports a lot of warning lines like this

Warning: Attempt to rename over same
inode: /backup/var/spool/cyrus/mail/a/user/archive/nagios/rdiff-backup.tmp.578 to /backup/var/spool/cyrus/mail/a/user/archive/nagios/608.

This happens since I moved emails about 1000 emails with Thunderbird
from the Inbox of User archive to the subfolder nagios.

I've activated

 delete_mode: delayed
 expunge_mode: delayed

in /etc/imap.conf therefore a

su - cyrus -c "/usr/sbin/unexpunge -l user.archive"

shows the moved messages in die Inbox as deleted and the same messages
in the nagios subfolder and these massages have the same inode

E-Mail in the Inbox:
# ls -li /var/spool/cyrus/mail/a/user/archive/1246. 
10488557 -rw------- 3 cyrus mail 1586 Mär 27
06:19 /var/spool/cyrus/mail/a/user/archive-bot-mxrelay/1246.

E-Mail in the Subfolder:
#ls -li /var/spool/cyrus/mail/a/user/archive/nagios/999. 
10488557 -rw------- 3 cyrus mail 1586 Mär 27
06:19 /var/spool/cyrus/mail/a/user/archive-bot-mxrelay/nagios/999.

Both have the same inode id.

diff /var/spool/cyrus/mail/a/user/archive/nagios/999.  /var/spool/cyrus/mail/a/user/archive/1246.
-> no output, same content.

Is that normal?

Ciao!
Marcus