I do assume both are the same people, since the manual mentions Taffy as being the main antagonist when Big Boss is the real one, and they both did the same thing so draw your conclusion.
The MG wikia itself has pages for his other three fake identities tho, so...
Well, I think I kinda get it... CaTaffy is Big Boss except he isn't, at least in the novelization, he's more of a character "loosely" based on the NES events, hence why he can be threated as a different character. At least I take it as it is.
Please vote for both or one of the 2 transparent png pictures of the infobox of Kronika the Keeper of Time (including the Lady Kronika-removebg.png picture under the infobox's secondary line named "Crowned" as I personally & honestly recommend).