package libqwt5-qt4-dev (not installed) failed to install/upgrade: trying to overwrite '/usr/lib/x86_64-linux-gnu/qt4/plugins/designer/libqwt_designer_plugin.so', which is also in package libqwt6 6.1.1-0ubuntu1

From DpkgTerminalLog.txt:
dpkg: error processing archive /var/cache/apt/archives/libqwt5-qt4-dev_5.2.3-1_amd64.deb (--unpack):
 trying to overwrite '/usr/lib/x86_64-linux-gnu/qt4/plugins/designer/libqwt_designer_plugin.so', which is also in package libqwt6 6.1.1-0ubuntu1

The bug is that the file '/usr/lib/x86_64-linux-gnu/qt4/plugins/designer/libqwt_designer_plugin.so' exists in both of these packages. Attempting to have both installed leads to a conflict.

Original description:
A DVB-T usb device was plugged in at the time.

ProblemType: Package
DistroRelease: Ubuntu 15.04
Package: libqwt5-qt4-dev (not installed)
ProcVersionSignature: Ubuntu 3.19.0-11.11-generic 3.19.3
Uname: Linux 3.19.0-11-generic x86_64
ApportVersion: 2.17.2-0ubuntu1
Architecture: amd64
Date: Thu Apr 30 23:27:56 2015
DuplicateSignature: package:libqwt5-qt4-dev:(not installed):trying to overwrite '/usr/lib/x86_64-linux-gnu/qt4/plugins/designer/libqwt_designer_plugin.so', which is also in package libqwt6 6.1.1-0ubuntu1
ErrorMessage: trying to overwrite '/usr/lib/x86_64-linux-gnu/qt4/plugins/designer/libqwt_designer_plugin.so', which is also in package libqwt6 6.1.1-0ubuntu1
InstallationDate: Installed on 2015-04-03 (27 days ago)
InstallationMedia: Ubuntu 15.04 "Vivid Vervet" - Beta amd64 (20150326)
RelatedPackageVersions:
 dpkg 1.17.25ubuntu1
 apt 1.0.9.7ubuntu4
SourcePackage: qwt5
Title: package libqwt5-qt4-dev (not installed) failed to install/upgrade: trying to overwrite '/usr/lib/x86_64-linux-gnu/qt4/plugins/designer/libqwt_designer_plugin.so', which is also in package libqwt6 6.1.1-0ubuntu1
UpgradeStatus: No upgrade log present (probably fresh install)