If you want to remove all doubt do as you have already been told and gently open the cartridge. In this way, will know with absolute certainty what you were really sold.
Anyway, there might be a plausible explanation to your mystery: when 'Fatal Fury Special' was released in Japan, the game was an incredible success (some Japanese fans say that in that year 'Fatal Fury' even surpassed 'Stret Fighter II', which was simply a second update of a two years old game).
In any case, as evidence of the popularity of 'Fatal Fury Special', there is the incredible amount of merchandising that was produced in those years: we speak of caps, clothes, containers, CDs, comics, guides, cards, VHS, puppets and the following year (1994) was projected also a movie exclusively for theaters, moreover, this game was converted for any platform existing at that time.
For the next chapter the expectations of fans were therefore very high and SNK therefore produced 'Fatal Fury 3': the sprites of the characters and backdrops were redesigned raising the bar of quality and even the dubbing and music were of the steps forward, not to mention the story and dialogues, which made 'FF3' look like a visual novel, rather than a simple arcade game, however, the playability was not at all convincing compared to its predecessor and in some places it was also an overly complicated experience.
SNK had therefore created a beautiful game to see and hear, but had not been as concerned with creating a 'tool' which was even more fun than the previous incarnations, so 'Fatal Fury 3' in the end flopped.
But precisely how big was this flop?
A user named Gemant (which now no longer attends this forum), had told me that the specialized magazines of that time, they had recorded the amateur scores of 'Fatal Fury Special' for a period I think of 13 years uninterrupted (so, while people were celebrating the new Xbox 360 and Wii, many were still playing 'FFS'), while with 'Fatal Fury 3' this recording of data was interrupted only a few months after the release of the game and honestly I have no trouble believing it, because even now the 'world' tournaments are held of 'Fatal Fury Special', while the third chapter is a memory that only we NEOGEO fans keep.
That being said, after the release of 'Fatal Fury 3', to SNK had remained with a large amount of unsold cartridges and since this company has always been of the 'you don't throw anything away' opinion, they used this unsold inventory to create 'Real Bout Fatal Fury', which they released not even nine months later.
So, the first edition of 'RB1' is a kind of official Frankestein, and that's why the game reuses the same and identical resources for the character sprites that already appeared in the previous chapter.
After its release, 'Real Bout Fatal Fury 1' was well received and was kept on the arcade market for more than a year, to then be converted on the home consoles of the time as well.
So here we are at the final stage, that will give a definitive answer to your question: I think at this point SNK has then consumed all the cartridges that had previously remained unsold, however, the game started to sell well and therefore it was necessary reprint new AES copies, which differ from the previous ones, because like your version contain the yellow label for the health warning.
This creating new games using an base and of the resources already existing, for SNK it was not a novelty, because this company did the exact same thing when 'Savage Reign' didn't sell: and that's why 'Kizuna Encounter' is such a rare game, because unlike 'RB1', the subsequent demands for 'Kizuna' must have been really non-existent, for not even get produce their own internal copy for the NEOGEO CD.