[Dovecot] Strange difference between mails delivered with dovecot-lda and lmtp

[Kamil Jońca]

For a long time I have had configuration where mails were fetched by
fetchmail then passed to exim and then passed to dovecot via lmtp.
Recently I remove dovecot module and mails are passed from exim to
dovecot via dovecot-lda
Yesterday I have some kind of accident and lost my .fetchids file so a
lot of mails were fetched again. 
During duplicate hunting I found something strange:
messages fetched yesterday (passed to dovecot with lda have additional
line) have additional line at the end:
for example 

--8<---------------cut here---------------start------------->8---
diff cur/1392241092.M478532P15313.alfa,S=13668,W=13925:2,a cur/1394814438.M978438P14745.alfa,S=13567,W=13823:2,a
1,6c1,4
< Return-Path: <system at przelewy24.pl>
< Delivered-To: <kjonca at localhost>
< Received: from alfa.kjonca
<       by alfa.kjonca (Dovecot) with LMTP id p94PDcTp+1LROwAApvcrCQ
<       for <kjonca at localhost>; Wed, 12 Feb 2014 22:38:12 +0100
< Received: from [127.0.0.1] (port=60632 helo=alfa.kjonca)
---
> Return-path: <system at przelewy24.pl>
> Envelope-to: kjonca at localhost
> Delivery-date: Fri, 14 Mar 2014 17:27:18 +0100
> Received: from [127.0.0.1] (port=45527 helo=alfa.kjonca)
9,10c7,8
<       id 1WDhVU-0003ys-75
<       for kjonca at localhost; Wed, 12 Feb 2014 22:38:12 +0100
---
>       id 1WOUgz-00015z-L0
>       for kjonca at localhost; Fri, 14 Mar 2014 17:10:41 +0100
13c11
<       for <kjonca at localhost> (single-drop); Wed, 12 Feb 2014 22:38:12 +0100 (CET)
---
>       for <kjonca at localhost> (single-drop); Fri, 14 Mar 2014 17:10:41 +0100 (CET)
30c28
< Message-Id: <E1WDhVU-0003ys-75 at alfa.kjonca>
---
> Message-Id: <E1WOUgz-00015z-L0 at alfa.kjonca>
256a255
> 
--8<---------------cut here---------------end--------------->8---

I'm somewhat confused with this. Is this normal?

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