You would need to check the documentation for the emulators you use, and in this case the individual Retroarch cores documentation.
 
	 
 
 
	Then you are doing something incorrectly, or they did import just fine and are in the right click menu as they should be, Launchbox imports what you tell it to, it doesnt randomly choose what to, and what not to import. If you added disc 1 and disc 2 they will both be imported if named correctly as to be identified as different discs for the same game.
 
	 
 
 
	No, thats not correct naming, you just want (Disk 1) (Disc 2) etc.