deja-dup report wrong version of duplicity

My setup :
dual boot between ubuntu 14.04 and arch , with a shared /home/<me> between the two.

The problem only occurs on Arch. The (pruned) output of pacman -Qi duplicity deja-dup :
deja-dup.gsetting is copied at the end

Name : duplicity
Version : 0.6.25-1

Name : deja-dup
Version : 32.0-1

duplicity/deja-dup works well under ubuntu, however, under arch, deja-dup complains that

"Déjà Dup Backup Tool requires at least version 0.6.23 of duplicity, but only found version 0.6.00".

However, the installed version of duplicity is 0.6.25. The log is completely empty.

org.gnome.DejaDup last-restore ''
org.gnome.DejaDup periodic true
org.gnome.DejaDup full-backup-period 90
org.gnome.DejaDup backend 'file'
org.gnome.DejaDup last-run '2014-10-01T02:21:51.959838Z'
org.gnome.DejaDup nag-check '2014-06-10T07:24:41.697121Z'
org.gnome.DejaDup prompt-check '2013-11-01T05:25:48.906134Z'
org.gnome.DejaDup root-prompt true
org.gnome.DejaDup include-list [...]
org.gnome.DejaDup exclude-list [...]
org.gnome.DejaDup last-backup '2014-10-01T02:21:51.959838Z'
org.gnome.DejaDup periodic-period 1
org.gnome.DejaDup delete-after 0
org.gnome.DejaDup.S3 id ''
org.gnome.DejaDup.S3 bucket ''
org.gnome.DejaDup.S3 folder 'desktop'
org.gnome.DejaDup.GDrive email ''
org.gnome.DejaDup.GDrive folder '/deja-dup/desktop_arch'
org.gnome.DejaDup.Rackspace username ''
org.gnome.DejaDup.Rackspace container 'desktop'
org.gnome.DejaDup.File path 'ftp://desktop_backup@192.168.11.3:21/NetBackup'
org.gnome.DejaDup.File short-name ''
org.gnome.DejaDup.File uuid ''
org.gnome.DejaDup.File icon ''
org.gnome.DejaDup.File relpath @ay []
org.gnome.DejaDup.File name ''
org.gnome.DejaDup.File type 'normal'