NAM-1975 possible alternate version found?

I picked up a bunch of MVS carts recently and I’ve finally got a test set up for them. First game I tested is NAM-1975. I have two carts of this title. One appears to match MAME exactly. The other has a weird sound problem. But also interesting on the one with bad sound, it appears to have some sound that I don’t find anywhere else. I watched several youtube videos of this game and none of them have this extra sound. I see only one NAM-1975 version in MAME. However when I look here:

https://www.mvs-scans.com/index.php/Nam_1975 I see two NAM-1975 sets referenced.

I recorded both games. The videos are only 30 seconds or so. Version 1 is the one that appears to match MAME. On version 2, the sound goes out, but the background music still continues. Then right near the end of the video, the sound comes back and some vocals are present that I don’t find elsewhere. Also, FYI, on the one with the bad sound, if I go into self-test, the left, right and center all work fine. You can view/listen to the videos here:

http://missilecommand.net/NEO-GEO-MVS/

When I look at the scans of the PCB in the top web site above, it appears all ICs are soldered. Does anyone have any knowledge of a second ROM version of this game? Anyone have any ideas or suggestions on the sound problems? I’ve never opened an MVS cart before. Is it pretty straight forward to dump? I imagine at a minimum, I have to desolder ROMs. Any guidance/advice appreciated. Thanks,

Joe (joemagiera at ameritech dot net)
joemagiera@ameritech.net

pretty sure it's Dr Muckley SE from the last boss fight.

Spoiler alert

It's the boss game over sfx aka what 95% of players will hear after getting to the last boss fight with Dr. Muckley. Fucking bullshit quarter stealer boss.