Drop GPL-2+ license from copyright as it hasn't been mentioned anywhere in headers.

debian/copyright

@@ -5,7 +5,7 @@ Source: https://github.com/lxde/lxqt-session
 Files: *
 Copyright: 2012-2015 LXQt team
            2010-2012 Razor team
-License: GPL-2.0+ and LGPL-2.1+
+License: LGPL-2.1+
 
 Files: debian/*
 Copyright: 2014-2015 Alf Gaida <agaida@siduction.org>
@@ -25,17 +25,3 @@ License: LGPL-2.1+
  .
  On Debian systems, the complete text of the GNU Lesser General
  Public License version 2.1 can be found in "/usr/share/common-licenses/LGPL-2.1".
-
-License: GPL-2.0+
- This program is free software; you can redistribute it and/or modify
- it under the terms of the GNU General Public License as published by
- the Free Software Foundation; either version 2 of the License, or
- (at your option) any later version.
- .
- This program is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- GNU General Public License for more details.
- .
- On Debian systems, the complete text of the GNU General Public License
- version 2 can be found in "/usr/share/common-licenses/GPL-2".