Aseprite always creates a new tile

Hi, I don’t quite understand the intermediate option in the tile creator.

The option says “modify and reuse existing tiles”, but it always creates new tiles for me.

Take a look at this video.
I have two identical tiles, and when I modify one of them, it creates a new tile based on the modified one. But it shouldn’t have created a new tile — it should have modified the existing ones (there are only two). The option clearly says “modify and reuse existing tiles”.

I know about the option to avoid creating new tiles, but that’s not what I want.
I want the existing tiles to be modified, and only if I draw on an empty tile, then a new tile should be created.