Duplicate launcher for flightgear (in bionic)

The flightgear package comes with two desktop launchers in bionic:
- /usr/share/applications/flightgear.desktop
- /usr/share/applications/org.flightgear.FlightGear.desktop
Both seem to run the same command (`fgfs --launcher`) and have the same icon; only, the second is translated to more languages and seems to be the one available in the git repository <https://github.com/FlightGear/flightgear/tree/next/package>. As a result, I now can see two identical FlightGear icons under Xubuntu menu > Games.

This does not seem to be the case for artful and previous versions, since the package contains a single application launcher there.

System:
Xubuntu 18.04 (bionic) 64-bit
flightgear 1:2018.1.1+dfsg-1

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: flightgear 1:2018.1.1+dfsg-1
ProcVersionSignature: Ubuntu 4.15.0-33.36-generic 4.15.18
Uname: Linux 4.15.0-33-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.20.9-0ubuntu7.2
Architecture: amd64
CurrentDesktop: XFCE
Date: Mon Sep 10 22:54:05 2018
InstallationDate: Installed on 2018-07-28 (44 days ago)
InstallationMedia: Xubuntu 18.04.1 LTS "Bionic Beaver" - Release amd64 (20180725)
SourcePackage: flightgear
UpgradeStatus: No upgrade log present (probably fresh install)