What does it means in slave? SyncRepl 2.4.19

[Nacho Díaz Asenjo <nacho@di.uc3m.es>]

  Hi!

   Yesterday, I upgraded my servers to Openldap 2.4.19, but in slave 
server i have some problems with synrepl. I can't make replica work, and 
i only can see this message continuosly.

  Oct 24 14:34:55 xxxx slapd[3657]: syncrepl_message_to_entry: rid=002 
mods check (mail: value #0 provided more than once)
  Oct 24 14:34:55 xxxx slapd[3657]: do_syncrepl: rid=002 rc 20 retrying 
(9 retries left)

   What does it means?

    Another question it's about GNU/Linux Debian 5.0. I upgraded from 
Etch to Lenny and the slapadd operation with a 100 MB LDIF took about 1h 
and the same operation in a Etch (Debian 4.0) usually takes only 5 
minutes. Anyone knows why?. I made tests with Berkeley DB 4.6 and 
Berkeley DB 4.4 and i obtained a similar result.

  Thanks for your atencion.