Editing Levels question

Hello everyone!

I've been fooling around a little bit with FF6LE Rogue Build, Version 20130525_115959. I've noticed that when I make a change to a map, it also changes other similar maps.
For example, if I add a chair to map  03D: Figaro Castle Basement 1, it also affects maps 03E-042. These are all maps that use the "Figaro Castle Basement".
I suppose my question is: Why does it do that? Is it important for these maps to be linked like this?

A related question would be for things like shops. Map 018 is the Narshe Weapons Shop, and Map 019 is the Narshe Armor shop. The maps are the exact same, save for the NPCs and message. Why did the programmers do it like that? Why not just put both NPCs in the same map? 

Is there a resource for FF6LE, or tilemap editing of this kind that I can refer to? Some kind of tutorial?

Thanks in advance for your help!

The map index sets which NPCs are on screen, dictates the random encounter table (and if there are random encounters or not), and handles on-entry event triggering.

Several maps share the same TILEMAP, though, which is why adding a chair to Figaro Castle Basement adds that chair to every map that uses the basement tilemap. This was done by the original FF6 development team to save space. It is to such an extreme that even rooms with completely different tilesets occur on the same map, such as the Magitek Research Factory's tube rooms (which look garbled when looking at the factory floor, and vice-versa).

The only way around it is to expand the ROM and make new maps from scratch; I can't help you with that personally but FF6LE Rogue CE is supposed to be able to handle map expansion. Beware of byte 17; it handles how the tilemap decides priority and should match whatever value the original map with that tileset had. I know there was an issue with that value not saving on Rogue CE, but I do not know if that bug has been corrected on the wiki version.

FF6LE CE can expand maps, tilemaps (space and number) as well as NPCs, event triggers and exits. It hasn't been tested really much with new maps (map IDs above 416) but you should be fine editing existing maps. Someone reported a saving bug with a new map they were making but I was never able to reproduce it, what happened is that the new map changes were not completely saved (it saved fine the times after with the same map). So it should be considered a beta release. This version fix the byte 17 bug mentioned above present in the original FF6LE and FF6LE Rogue:

 FF6LE-CE.zip (153.93 KB, 4 downloads)