Yes, that's correct. with your current project open go to File>open or Open recent..
and once you've selected a file Logic will ask if you want to close the current song or not. Choose "don't close"
and then you will have two projects open.
However, when you switch between the two projects Logic loads up all the audio files as if you are opening the song from scratch - so there is a delay between switching song.
Also, I imagine - though am not sure - your cpu will take a bigger hit than if you only had one song open. Might be a consideration....depending on why you want to have two songs open simultaneously.