[Dovecot] sieve, vacation - lda-dupes being ignored?

[Per Jessen]

Environment: dovecot 2.0.9, postfix 2.6, Pigeonhole 0.2.2

I'm in the process of setting up vacation auto-reply for the first time,
(it's that time of the year) and it looks like .dovecot.lda-dupes is 
being updated, but not read (or just ignored). 

my vacation script:

require ["vacation","variables"];

# get hold of the subject
if header :matches "Subject" "*" { set "subj" "${1}"; }

vacation
    # Reply at most once a week to a same sender
    :days 7
    :subject "Re: ${subj} (automatic reply; I am out of the office)"
    :addresses "pjes...@example.com"
    :mime text:

The script works fine, but I get a reply for every msg sent:

# grep sieve.*sent  /var/log/mail
Jul 26 10:17:26 neon dovecot: lmtp(4367, per....@example.com): 
Pj0iEbx3Lk4PEQAA0G3O/A: sieve: msgid=<4e2e7807.8000...@example.com>: sent 
vacation response to  
<SRS0+9c3c5bbcdb70e56f=2N=example.com=per.jes...@srs.example.org>
Jul 26 10:29:06 neon dovecot: lmtp(10165, per....@example.com): 
Hbm3DhJ6Lk61JwAA0G3O/A: sieve: msgid=<4e2e7abf.3090...@example.com>: sent 
vacation response to 
<SRS0+9c3c5bbcdb70e56f=2N=example.com=per.jes...@srs.example.org>
Jul 26 11:09:41 neon dovecot: lmtp(2496, per....@example.com): 
WPtRMVWELk7ACQAA0G3O/A: sieve: msgid=<4e2e8447.9070...@example.com>: sent 
vacation response to  
<SRS0+9c3c5bbcdb70e56f=2N=example.com=per.jes...@srs.example.org>
Jul 26 11:32:26 neon dovecot: lmtp(15648, per....@example.com): 
7pQrLKqJLk4gPQAA0G3O/A: sieve: msgid=<4e2e8999.8040...@example.com>: sent 
vacation response to 
<SRS0+9c3c5bbcdb70e56f=2N=example.com=per.jes...@srs.example.org>
Jul 26 11:39:12 neon dovecot: lmtp(18845, per....@example.com): 
ds9CDfeKLk6dSQAA0G3O/A: sieve: msgid=<4e2e8b30.1070...@example.com>: sent 
vacation response to 
<SRS0+9c3c5bbcdb70e56f=2N=example.com=per.jes...@srs.example.org>
Jul 26 11:42:40 neon dovecot: lmtp(21484, per....@example.com): 
eXZHOw+MLk7sUwAA0G3O/A: sieve: msgid=<4e2e8bf9.7010...@example.com>: sent 
vacation response to 
<SRS0+9c3c5bbcdb70e56f=2N=example.com=per.jes...@srs.example.org>
Jul 26 15:26:25 neon dovecot: lmtp(19216, per....@example.com): 
Wma/OIDALk4QSwAA0G3O/A: sieve: msgid=<4e2ec06f.5060...@example.com>: sent 
vacation response to 
<SRS0+9c3c5bbcdb70e56f=2N=example.com=per.jes...@srs.example.org>


Is there a way to dump the contents of lda-dupes in clear text?

thanks
Per Jessen, Zürich