Two Telegram messengers in the Unity Launcher

Solution 1:

For some reason, Telegram makes two .desktop files when installed; one in /usr/share/applications and one in ~/.local/share/applications

I now just rename the local one so that it isn't read:

mv ~/.local/share/applications/telegramdesktop.desktop ~/.local/share/applications/telegram

This immediately kills the second icon.

You may have to repeat when Telegram updates itself, as it will regenerate the file

Solution 2:

Right click the unwanted one and choose unlock from launcher. This approach will remove it from the launcher but should be risk free and doesn't require editing anything.