FF1 appears to load backgruond tiles in chunks of 2k. The left pattern table is 4k, so the first 128 tiles are loaded depending on location type (castle, cave, etc...) while the last 128 tiles are constant (always representing the font and window borders).
But they needed a couple of more tiles for the font in the original JP version which has full hiragana, katakana, many symbols and some letters. 128 tiles weren't enough so they stole a couple of tiles in the first 2k for this. The USA version, and thus all the hacks and translations based on it, inherited this. The extra tiles have to be duplicated because they need to be there no matter which tile page is loaded for the first 2k.
You could probably hack the game so that it loads pages of the correct size, and free those tiles up to better usage.