How do I open multiple instances of an app?

I have a *.app

If I open it, from the dock, or from Finder, it opens. I want to open ANOTHER second running instance.

If I open it, from the dock or from the Finder the second time, now it simply focuses it.

One Windows and Ubuntu you can simply hold CTRL and click it and a second instance will open. How do I do that on OSX?

NOTE: I tried the open -n trick and it doesn't work.

Because OSX is just unix, you can use a terminal to run the original binary that's stored in the *.app directory. A la

/Applications/TextEdit.app/Contents/MacOS/TextEdit &

Keep in mind some applications use databases to store their data which may cause conflicts or loss of data.

If you don't want to use the terminal, then you can make a shortcut icon that runs this command using the built in Automater app