[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 "pjessen at 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.acm at example.com): Pj0iEbx3Lk4PEQAA0G3O/A: sieve: msgid=<4E2E7807.8000301 at example.com>: sent vacation response to  <SRS0+9c3c5bbcdb70e56f=2N=example.com=per.jessen at srs.example.org>
Jul 26 10:29:06 neon dovecot: lmtp(10165, per.acm at example.com): Hbm3DhJ6Lk61JwAA0G3O/A: sieve: msgid=<4E2E7ABF.3090804 at example.com>: sent vacation response to <SRS0+9c3c5bbcdb70e56f=2N=example.com=per.jessen at srs.example.org>
Jul 26 11:09:41 neon dovecot: lmtp(2496, per.acm at example.com): WPtRMVWELk7ACQAA0G3O/A: sieve: msgid=<4E2E8447.9070007 at example.com>: sent vacation response to  <SRS0+9c3c5bbcdb70e56f=2N=example.com=per.jessen at srs.example.org>
Jul 26 11:32:26 neon dovecot: lmtp(15648, per.acm at example.com): 7pQrLKqJLk4gPQAA0G3O/A: sieve: msgid=<4E2E8999.8040800 at example.com>: sent vacation response to <SRS0+9c3c5bbcdb70e56f=2N=example.com=per.jessen at srs.example.org>
Jul 26 11:39:12 neon dovecot: lmtp(18845, per.acm at example.com): ds9CDfeKLk6dSQAA0G3O/A: sieve: msgid=<4E2E8B30.1070804 at example.com>: sent vacation response to <SRS0+9c3c5bbcdb70e56f=2N=example.com=per.jessen at srs.example.org>
Jul 26 11:42:40 neon dovecot: lmtp(21484, per.acm at example.com): eXZHOw+MLk7sUwAA0G3O/A: sieve: msgid=<4E2E8BF9.7010301 at example.com>: sent vacation response to <SRS0+9c3c5bbcdb70e56f=2N=example.com=per.jessen at srs.example.org>
Jul 26 15:26:25 neon dovecot: lmtp(19216, per.acm at example.com): Wma/OIDALk4QSwAA0G3O/A: sieve: msgid=<4E2EC06F.5060307 at example.com>: sent vacation response to <SRS0+9c3c5bbcdb70e56f=2N=example.com=per.jessen at srs.example.org>


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

thanks
Per Jessen, Zürich