Hello!
I created a .desktop entry for blender so that I can also launch blender from the application menu.
Works so far. 
My problem is that when I click the blender launcher again I want to open a second instance of blender, instead it just switches to the other instance 
I’m on Lubuntu 14.10x64
A new instance will be open when you click with MMB on most apps in ubuntu,Unity panel that is.
I’m not using Unity, but Cinnamon instead. The launchers should work the same I would think. On Cinnamon you need to edit the launcher to change versions, or create a new one. In Cinnamon you just right click the launcher and select “Edit”, then it’s just a matter of changing the binary that the launcher points to.
i would just open a terminal and start a new instance that way
it is still the easiest and best way
Well I’m not on Mint or Unity I’m on LXDE using Lubuntu however mmb menu also opens a new instance.
But actually I’m using kupfer to start applications.
Well I figured out how to do that with kupfer too.
Still what I really want is a launcher independent solution, probably directly written into the exec of the .desktop file