dock menu allows multiple, overlapping instances

This appears to be an interaction between XFCE and Cairo-Dock.

If in XFCE, one goes to XFCE-> Settings-> Session and Startup-> Application Autostart, and sets it to launch /usr/bin/cairo-dock, then one still has the option in Cairo-Dock to "+ Launch Cairo-Dock on startup". This gives two overlapping instances of cairo-dock, See the attached screenshot.

When checking to see if cairo-dock is already added to XFCE's startup applications, it should look to find manually added instances as well.

$ apt-cache policy cairo-dock
cairo-dock:
  Installerad: 3.3.99.beta1.2.really.3.3.2-0ubuntu2.1
  Kandidat: 3.3.99.beta1.2.really.3.3.2-0ubuntu2.1
  Versionstabell:
 *** 3.3.99.beta1.2.really.3.3.2-0ubuntu2.1 0
        500 http://fi.archive.ubuntu.com/ubuntu/ trusty-updates/universe amd64 Packages
        100 /var/lib/dpkg/status
     3.3.99.beta1.2.really.3.3.2-0ubuntu2 0
        500 http://fi.archive.ubuntu.com/ubuntu/ trusty/universe amd64 Packages

$ lsb_release -rd
Description: Ubuntu 14.04.2 LTS
Release: 14.04

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: cairo-dock 3.3.99.beta1.2.really.3.3.2-0ubuntu2.1
ProcVersionSignature: Ubuntu 3.16.0-41.57~14.04.1-generic 3.16.7-ckt11
Uname: Linux 3.16.0-41-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.11
Architecture: amd64
CompositingMetacity: No value set for `/apps/metacity/general/compositing_manager'
Date: Sat Jul 4 16:13:12 2015
InstallationDate: Installed on 2015-06-28 (5 days ago)
InstallationMedia: Xubuntu 14.04.2 LTS "Trusty Tahr" - Release amd64 (20150218.1)
PackageArchitecture: all
PciDisplay: 02:00.0 VGA compatible controller [0300]: NVIDIA Corporation C79 [GeForce 9400] [10de:0861] (rev b1) (prog-if 00 [VGA controller])
RelatedPackageVersions:
 xserver-xorg N/A
 libgl1-mesa-glx N/A
 libdrm2 2.4.60-2~ubuntu14.04.1
 xserver-xorg-video-intel N/A
 xserver-xorg-video-ati N/A
SourcePackage: cairo-dock
UpgradeStatus: No upgrade log present (probably fresh install)
WM: No value set for `/desktop/gnome/applications/window_manager/current'
glxinfo: Error: [Errno 2] No such file or directory: 'glxinfo'
system: distro = Ubuntu, architecture = x86_64, kernel = 3.16.0-41-generic