dovecot replication duplicates

I got mailbox on both servers which are connected with eachother for dovecot replication. When mail comes to mailbox only on one server replication works ok, but when there is new mail on second server during replication I got this error:

dovecot: dsync-server(<<MAILBOX>>): Warning: Mailbox INBOX doesn't match previous state: Unexpected GUID mismatch for UID=237805: 58703d2e76898b588d7a0000c278a7cb != 89545203226fed6a8a3cde4a98690e96(guid128, orig=89545203226fed6a8a3cde4a98690e96) (dsync must be run again without the state)

and as a result i got this mail replicated in 2-3 copies on both sides.

Any ideas why?

my replicator config:

service replicator {
  process_min_avail = 1

  unix_listener replicator-doveadm {
    mode = 0660
    group = vmail
  }
}

service aggregator {
  fifo_listener replication-notify-fifo {
    user = vmail
  }
  unix_listener replication-notify {
    user = vmail
  }
}

service doveadm {
  inet_listener {
    port = 8999
    ssl = yes
  }
}

service config {
  unix_listener config {
    user = vmail
  }
}

plugins.conf

...
mail_replica = tcps:HOST_ONE
replication_max_conns = 1
#  replication_sync_timeout = 2s
replication_dsync_parameters = -d -N -l 30 -U
...

same config is on both servers (besides of mail_replica which is set for every host to point another one)