This appears to be https://bugzilla.gnome.org/show_bug.cgi?id=684249 though the initial report there is a little different. If it is the same, it's fixed in 3.6.1 (I'm using 3.6.0 from Ubuntu 12.10). It would be good to have this fixed in Ubuntu because it's a real pain to keep deleting the duplicate.
** Bug watch added: GNOME Bug Tracker #684249 https://bugzilla.gnome.org/show_bug.cgi?id=684249 -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1086411 Title: reply to a message duplicates signature To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/evolution/+bug/1086411/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs