sundogak

@BigBearPoetThis is an issue across all emulation for CD-i as the digital video cartridge hardware has not been emulated.  Not likely to be resolved anytime soon as specs for DVC are sparse.
List of CD-i programs that need DVC to run. 

If doesn't work in CEMU won't ever work in LB.  Verify the games work in CEMU and if not likely encryption issue. 
The main issue is you have a mixture of different file types. Encrypted files such as WUX, WUD, WUP, or folders with files like "*.app" need to have an encryption key in the Keys.txt file in the CEMU base directory (see snap below) OR they need to be decrypted (which still needs keys but only one time).

WUP to my knowledge (one you listed in your snap as shows NUS in TItle Manager) is encrypted (if only see "*.app files" or one file with a WUP extension).  NUS files within a folder can be either encrypted or not depending on tool used to download from servers.  Keys are specific to the game/region. You must have SOME keys as you said you were able to launch some games within CEMU. However, you must also be missing some as your WUX file isn't launching within CEMU.  A Google search for "Wii U Keys latest" will get you a file about the 4th one down (backup your existing one!). In the keys.txt text file if you do search for the title ID for that game and if it is present then CEMU will run game.  RPX files are decrypted game files (and no longer need keys). The default LB setup assumes you are pointing to RPX file, or decrypted WUA or encrypted WUX/WUD file with corresponding key in CEMU.
So you have few choices. Make sure you have keys so CEMU can be used to launch the encrypted file/folder, use install feature in CEMU which will decrypt NUS files, or use a tool like CDecrypt (use google, there are also many other tools around) which makes the folders and RPX files needed. WUA files are also option as they are decrypted and compressed into one file but they can only be used for emulation (not for real Wii U).  If just doing emulation, WUA is easiest and smallest and "all in one" file. WUA files you can use LB default emulator setup and simply point to WUA file. You can also make WUA files from within CEMU via Tools menu and Title list.
If you have a few games working in CEMU and don't want to bother with figuring out the above or downloading other files, or decrypting, then this way of launching the game in LB will always work no matter the type as it uses CEMU's title list to launch the game (again must work in CEMU and be installed so see in Game list in CEMU).  This process differs from default settings for CEMU in LB.  CEMU will launch any game if you use the -t flag and the corresponding title ID in command line. See note at end about drawbacks, as time consuming if talking 100s of games.
We can use this process in LB as follows:
1) Setup CEMU emulator to use the "-t" (title) option.  It looks like this (Note the -t option vs LB default which uses -g which indicates path to game files).  Also make sure to check the two boxes below this to remove quotes and folder path. 

Now you need to point LB for the "ROM" or "Game" to a pointer file that contains the title ID in the file name (not inside the text file).  It will look something like this and where you place it doesn't matter as long as you point to this file in LB.

Where you get the Title IDs is within CEMU. Fortunately, it has a "right-click" option to copy the Title ID. You can then paste this in the dummy text file name.  What you are ultimately telling CEMU is to launch a game with the title ID in its installed DB.

 
In my example I pasted in the Title ID for "6-Hand Video Poker" into the text file name (no contents inside text file) which is 00050000101d7a00.txt
Import this text file as the game "ROM".  Ignore my path I have below, as can be any folder/location you choose (you are using CEMU to figure stuff out). 

We told LB in emulator setup to ignore the extension (txt in this case) and to drop the path. This then tells CEMU to launch with title 00050000101d7a00
***The hassle with this process is having to use the Title IDs and dummy pointer files; but the benefit is it doesn't care about folder, files, or encryption as long as works in CEMU if you have mix of various file types. LB will also not know what the real game title is so you will have to override that on import so it can match in DB.  If you are trying to install 100s of files then again this is a pain (just get a WUA or WUX set then which has game titles in files that LB can figure out on import).
If have WUX files and not seeing in CEMU game list make sure to add their game folder path in CEMU (must still have keys in the keys.txt file):

Hmm..always something with MAME!  Nothing on your end, I see same issue.  I  just never noticed with other software setups.  My understanding was MAME team made unique naming for zip files, but suspect with software set that is less of a good assumption and/or it is a goof up that wasn't noticed.  I never hit this on systems like Apple II, GS, and Atari 800.  I did a cursory click through on some other systems and seems media is either differently named or no overlap in naming. But as you noted SORD has some dupe names as well.  Systems like Atari 800 did have duplicates for Zaxxon cart and cassette but the Atari 8-bit cassette subsystem isn't working in MAME so never conflicted.  
In case of VZ 200/300, if you do a -listemedia the short media name is "Snapshots = dump" and "Cassette=cass" so like you said it is taking the first media type HASH file alphabetically which happens to be cassette vs dump.  If I delete the cassette version (like Invaders) even if pointing in LB to the zip file in dump directory then it will error out that cassette version is missing.  It is doing exactly what supposed to in that it is looking at HASH file and matching zip file name but in this case breaks due to duplicate names. 
Thus, sadly my comment above is with a caveat that on some systems you may still be stuck using the media type.  Or for those few oddballs that are named the same explicitly, setup a command path with media flag in LB.  For systems like Apple II where you have multiple discs on games the HASH (no media flag) method is great because it auto loads discs into all available floppy slots automatically in MAME vs having to manually load each via command line.  
Nutshell for at least this system (you were right Spycat!), use the media flag like you said above unless really want to use the cassette version:
vz300 -mem laser310_16k -dump Made edits to prior post to clarify for others down the road.