Popup confirms installation after cancel in password window

Description: Ubuntu 16.04.1 LTS
Release: 16.04

gnome-software:
  Installiert: 3.20.1+git20160617.1.0440874.ubuntu-xenial-0ubuntu1~16.04.1
  Installationskandidat: 3.20.1+git20160617.1.0440874.ubuntu-xenial-0ubuntu1~16.04.1
  Versionstabelle:
 *** 3.20.1+git20160617.1.0440874.ubuntu-xenial-0ubuntu1~16.04.1 500
        500 http://de.archive.ubuntu.com/ubuntu xenial-updates/main amd64 Packages
        100 /var/lib/dpkg/status
     3.20.1+git20160420.1.ca63436.ubuntu-xenial-0ubuntu2 500
        500 http://de.archive.ubuntu.com/ubuntu xenial/main amd64 Packages

Expected:
When I start installing virtualbox via gnome-software and press "Cancel" in the window where you enter your user password, I expect the installation to cancel silently.

What happened:
When I start installing virtualbox via gnome-software and press "Cancel" in the window where you enter your user password, a popup appears *sometimes*, confirming the installation of virtualbox.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: gnome-software 3.20.1+git20160617.1.0440874.ubuntu-xenial-0ubuntu1~16.04.1
ProcVersionSignature: Ubuntu 4.4.0-38.57-generic 4.4.19
Uname: Linux 4.4.0-38-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.1
Architecture: amd64
CurrentDesktop: Unity
Date: Wed Oct 5 14:00:06 2016
EcryptfsInUse: Yes
ExecutablePath: /usr/bin/gnome-software
InstallationDate: Installed on 2016-08-10 (56 days ago)
InstallationMedia: Ubuntu 16.04.1 LTS "Xenial Xerus" - Release amd64 (20160719)
ProcEnviron:
 LANGUAGE=de_DE
 PATH=(custom, user)
 XDG_RUNTIME_DIR=<set>
 LANG=de_DE.UTF-8
 SHELL=/bin/bash
SourcePackage: gnome-software
UpgradeStatus: No upgrade log present (probably fresh install)