launcing terminal from launcher creates a duplicate icon for the running instance

When opening the terminal app from the launcher, a new icon for the running instance is created instead of using the pinned one.

ProblemType: Bug
DistroRelease: Ubuntu 16.10
Package: unity 7.5.0+16.10.20160906.1-0ubuntu1
ProcVersionSignature: Ubuntu 4.4.0-9136.55-generic 4.4.16
Uname: Linux 4.4.0-9136-generic x86_64
.tmp.unity_support_test.0:

ApportVersion: 2.20.3-0ubuntu7
Architecture: amd64
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
CompositorRunning: compiz
CompositorUnredirectDriverBlacklist: '(nouveau|Intel).*Mesa 8.0'
CompositorUnredirectFSW: true
CurrentDesktop: Unity:Unity7
Date: Thu Sep 29 14:15:05 2016
DistUpgraded: 2016-09-20 10:45:11,503 DEBUG Running PostInstallScript: './xorg_fix_proprietary.py'
DistroCodename: yakkety
DistroVariant: ubuntu
GraphicsCard:
 Intel Corporation Haswell-ULT Integrated Graphics Controller [8086:0a16] (rev 0b) (prog-if 00 [VGA controller])
   Subsystem: Dell Haswell-ULT Integrated Graphics Controller [1028:05cb]
InstallationDate: Installed on 2016-07-13 (78 days ago)
InstallationMedia: Ubuntu 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.1)
MachineType: Dell Inc. Latitude E7440
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.4.0-9136-generic root=UUID=cdbcc31e-7f7d-4ad9-b46d-5299d8f494ec ro quiet splash vt.handoff=7
SourcePackage: unity
UpgradeStatus: Upgraded to yakkety on 2016-09-20 (9 days ago)
dmi.bios.date: 05/19/2015
dmi.bios.vendor: Dell Inc.
dmi.bios.version: A15
dmi.board.name: 0JNYGR
dmi.board.vendor: Dell Inc.
dmi.board.version: A00
dmi.chassis.type: 9
dmi.chassis.vendor: Dell Inc.
dmi.modalias: dmi:bvnDellInc.:bvrA15:bd05/19/2015:svnDellInc.:pnLatitudeE7440:pvr01:rvnDellInc.:rn0JNYGR:rvrA00:cvnDellInc.:ct9:cvr:
dmi.product.name: Latitude E7440
dmi.product.version: 01
dmi.sys.vendor: Dell Inc.
version.compiz: compiz 1:0.9.13.0+16.10.20160818.2-0ubuntu2
version.ia32-libs: ia32-libs N/A
version.libdrm2: libdrm2 2.4.70-1
version.libgl1-mesa-dri: libgl1-mesa-dri 12.0.3-1ubuntu1
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 12.0.3-1ubuntu1
version.xserver-xorg-core: xserver-xorg-core 2:1.18.4-1ubuntu6
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.10.2-1ubuntu1
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:7.7.1-1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917+git20160706-1ubuntu1
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.12-2