Not shit. 2 is 2, and outside of Japan, I do not remember where... 2 is the alternate name for 4. I don't remember 5 ever having an alternate name.
What started the whole number fuck ups was the fact that FF3 never was released in the westarn market. 3 was never released because all the main characters in the game are males and the market was not so accepting of such things in games of that type back then. A similar thing happened with the third Lunar game (the series' obligatory gaiden), no-one thought that a game with a magic school and 90%, non busty, female main characters would have sold (outside of Japan) at the time.