Middle button emulation works on lower buttons but not upper buttons on HP EliteBook 9470m

[x]

On an HP EliteBook Folio 9470m laptop, middle-button emulation (pressing the left and right buttons simultaneously) works for the two buttons "below" the trackpad (farther away from the keyboard) but not for the two buttons "above" the trackpad (closer to the keyboard). Both sets of left and right buttons function normally as left and right "mouse" buttons when not pressed together. (Pressing the upper-left and lower-right (or vice-versa) buttons simultaneously also does not simulate a middle-button event.)

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: xserver-xorg-input-synaptics 1.7.4-0ubuntu1
ProcVersionSignature: Ubuntu 3.13.0-35.62-generic 3.13.11.6
Uname: Linux 3.13.0-35-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.4
Architecture: amd64
CurrentDesktop: Unity
Date: Tue Sep 16 11:55:55 2014
DistUpgraded: Fresh install
DistroCodename: trusty
DistroVariant: ubuntu
InstallationDate: Installed on 2014-09-15 (0 days ago)
InstallationMedia: Ubuntu 14.04.1 LTS "Trusty Tahr" - Release amd64 (20140722.2)
MachineType: Hewlett-Packard HP EliteBook Folio 9470m
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.13.0-35-generic root=UUID=a2fbf74f-8769-488a-afa2-0d09cb2c939e ro quiet splash vt.handoff=7
SourcePackage: xserver-xorg-input-synaptics
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 01/13/2014
dmi.bios.vendor: Hewlett-Packard
dmi.bios.version: 68IBD Ver. F.48
dmi.board.name: 18DF
dmi.board.vendor: Hewlett-Packard
dmi.board.version: KBC Version 62.18
dmi.chassis.asset.tag: CNU4229TKY
dmi.chassis.type: 10
dmi.chassis.vendor: Hewlett-Packard
dmi.modalias: dmi:bvnHewlett-Packard:bvr68IBDVer.F.48:bd01/13/2014:svnHewlett-Packard:pnHPEliteBookFolio9470m:pvrA1029D1103:rvnHewlett-Packard:rn18DF:rvrKBCVersion62.18:cvnHewlett-Packard:ct10:cvr:
dmi.product.name: HP EliteBook Folio 9470m
dmi.product.version: A1029D1103
dmi.sys.vendor: Hewlett-Packard
version.compiz: compiz 1:0.9.11.2+14.04.20140714-0ubuntu1
version.ia32-libs: ia32-libs N/A
version.libdrm2: libdrm2 2.4.52-1
version.libgl1-mesa-dri: libgl1-mesa-dri 10.1.3-0ubuntu0.1
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 10.1.3-0ubuntu0.1
version.xserver-xorg-core: xserver-xorg-core 2:1.15.1-0ubuntu2.1
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.8.2-1ubuntu2
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:7.3.0-1ubuntu3.1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.910-0ubuntu1.1
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.10-1ubuntu2
xserver.bootTime: Mon Sep 15 15:03:24 2014
xserver.configfile: default
xserver.errors:

xserver.logfile: /var/log/Xorg.0.log
xserver.outputs:
 product id 12606
 vendor AUO
xserver.version: 2:1.15.1-0ubuntu2.1

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.