That's it. Can this be initiated two times to open two separated solutions at the same time?
By default an
.app runs as a single instance/single document mode, its the Cocca way of life and MonoDevelop/Xamarin Studio/Visual Studio for Mac follows that paradigm.
open -n MySolution.sln
-n = Open a new instance of the application(s) even if one is already running.
From @TomGilder comment: